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Soleymanzadeh M, Rafizadeh SM, Ghochani G, Mafi AR, Nazari M, Rajabi MT. Biomechanical changes of the cornea after orbital decompression in thyroid-associated orbitopathy measured by corvis ST. Sci Rep 2024; 14:16930. [PMID: 39043930 PMCID: PMC11266539 DOI: 10.1038/s41598-024-68081-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Accepted: 07/19/2024] [Indexed: 07/25/2024] Open
Abstract
This study aims to investigate the changes in ocular biomechanical factors in patients with inactive thyroid eye disease (TED) who undergo orbital decompression surgery. This observational prospective study include 46 eyes of 31 patients with inactive TED undergoing orbital decompression at a tertiary university hospital from October 2021 to September 2023. All participants underwent a full ophthalmic examination, and a biomechanical examination was performed using corvis ST at baseline, 1 month, and 3 months postoperatively. The study participants had a mean age of 45 ± 11.6 years, and 58.1% of them were female. The second applanation time (A2T) increased from baseline to postoperative month 1 and continued to increase to postoperative month 3 (P < 0.001). The first applanation velocity (A1V), highest concavity (HC) peak distance, and pachymetry parameters also increased from postoperative month 1 to postoperative month 3 (P = 0.035, P = 0.005, and P = 0.031, respectively). The HC time increased from baseline to postoperative month 3 (P = 0.027). Other changes were statistically insignificant. The P-values were adjusted according to biomechanically corrected intraocular pressure (bIOP). Baseline Hertel significantly influenced A2 time (P < 0.001). Our findings suggest that ocular biomechanical parameters may change following decompression surgery in patients with inactive TED. Specifically, an increase in A2T, A1V, and HC peak distance suggests a decrease in corneal stiffness, although the increased HC time contradicts this. It is recommended to postpone keratorefractive or intraocular lens implantation surgeries until corneal biomechanics stabilize after decompression surgery for optimal results.
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Affiliation(s)
- Mahdi Soleymanzadeh
- Department of Oculo-Facial Plastic and Reconstructive Surgery, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, 1336616351, Iran
| | - Seyed Mohsen Rafizadeh
- Department of Oculo-Facial Plastic and Reconstructive Surgery, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, 1336616351, Iran.
| | - Ghazal Ghochani
- Department of Oculo-Facial Plastic and Reconstructive Surgery, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, 1336616351, Iran
| | - Amir Reza Mafi
- Department of Oculo-Facial Plastic and Reconstructive Surgery, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, 1336616351, Iran
| | - Mohammadreza Nazari
- Department of Oculo-Facial Plastic and Reconstructive Surgery, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, 1336616351, Iran
| | - Mohammad Taher Rajabi
- Department of Oculo-Facial Plastic and Reconstructive Surgery, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, 1336616351, Iran
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Flockerzi E, Seitz B. Keratectasia severity staging and progression assessment based on the biomechanical E-staging. EYE AND VISION (LONDON, ENGLAND) 2024; 11:24. [PMID: 38946004 PMCID: PMC11215830 DOI: 10.1186/s40662-024-00392-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 06/07/2024] [Indexed: 07/02/2024]
Abstract
Until recently, corneal topography has been the gold standard in detecting keratectasia and monitoring its progression. The recently introduced ABCD tomographic keratoconus staging system focuses on anterior ("A") and posterior ("B") radius of curvature, thinnest corneal thickness ("C"), best-corrected visual acuity with spectacles ("D") and is supplemented with the introduction of the biomechanical E-staging (BEST, "E"). The need for biomechanical staging arose from the fact of altered biomechanical characteristics of keratectasia in comparison to healthy corneas. Ectatic corneas usually exhibit a biomechanical weakening and greater deformation than healthy corneas when exposed to a biomechanical stressor such as a standardized air puff indentation as provided by the Corvis ST® (CST, Oculus, Wetzlar, Germany). The BEST is based on the linear term of the Corvis Biomechanical Index (CBI) and provides a biomechanical keratoconus severity staging and progression assessment within the CST software. This review traces the development of the BEST as an addition to the tomographic ABCD staging system and highlights its strengths and limitations when applied in daily practice for the detection, monitoring and progression assessment in keratectasia.
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Affiliation(s)
- Elias Flockerzi
- Department of Ophthalmology, Saarland University Medical Center, Kirrberger Straße, Building 22, 66421, Homburg, Germany.
| | - Berthold Seitz
- Department of Ophthalmology, Saarland University Medical Center, Kirrberger Straße, Building 22, 66421, Homburg, Germany
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Esporcatte LPG, Salomão MQ, Lopes BT, Sena N, Machado AP, Vinciguerra P, Vinciguerra R, Ambrósio R. Keratoconus and Corneal Ectasia with Relatively Low Keratometry. Ophthalmol Ther 2024; 13:2023-2035. [PMID: 38824471 PMCID: PMC11178753 DOI: 10.1007/s40123-024-00964-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 05/01/2024] [Indexed: 06/03/2024] Open
Abstract
INTRODUCTION The study aims to demonstrate and estimate the prevalence of clinical corneal ectasia and keratoconus (KC) in patients with relatively low keratometry (low-K KC). METHODS In a retrospective, analytical, and non-interventionist study, one eye was randomly selected from 1054 patients from the original Tomographic Biomechanical Index (TBIv1) study and the external validation (from Rio de Janeiro, Brazil, and Milan, Italy clinics). Patients were stratified into three groups. Group 1 included 736 normal patients, and groups 2 and 3 included 318 patients with clinical KC in both eyes, divided into low-K KC (90 patients) and high-K KC (228 patients), respectively. All patients underwent a comprehensive ophthalmological evaluation along with Pentacam and Corvis ST (Oculus, Wetzlar, Germany) examinations. Cases with maximum mean zone 3 mm keratometry (Kmax zone mean 3 mm) lower than 47.6 diopters (D) were considered as low-keratometry keratoconus, and cases with Kmax zone mean 3 mm higher than 47.6 D were regarded as high-keratometry keratoconus. RESULTS Ninety (28.30%) of the 318 KC group presented ectasia with low-keratometric values (low-Kmax). The average age in the normal group was 39.28 years (range 6.99-90.12), in the low-Kmax KC group it was 37.49 (range 13.35-78.45), and in the high-Kmax KC group it was 34.22 years (range 12.7-80.34). Mean and SD values and median (range), respectively, of some corneal tomographic and biomechanical parameters evaluated from the low-Kmax KC group were as follows: Belin-Ambrósio enhanced ectasia display (BAD-D) 3.79 ± 1.62 and 3.66 (0.83-9.73); Pentacam random forest index (PRFI) 0.78 ± 0.25 and 0.91 (0.05-1); corneal biomechanical index (CBI) 0.58 ± 0.43 and 0.75 (0-1); TBI 0.93 ± 0.17 and 1 (0.35-1); and stiffness parameter at A1 (SP-A1) 86.16 ± 19.62 and 86.05 (42.94-141.66). CONCLUSION Relatively low keratometry, with a Kmax lower than 47.6 D, can occur in up to 28.30% of clinical keratoconus. These cases have a less severe presentation of the disease. Future studies involving larger populations and prospective designs are necessary to confirm the prevalence of keratoconus with low keratometry and define prognostic factors in such cases.
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Affiliation(s)
- Louise Pellegrino G Esporcatte
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rua Conde de Bonfim 211/712, Rio de Janeiro, RJ, 20520-050, Brazil
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | - Marcella Q Salomão
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rua Conde de Bonfim 211/712, Rio de Janeiro, RJ, 20520-050, Brazil
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
- Instituto Benjamin Constant, Rio de Janeiro, Brazil
| | - Bernardo T Lopes
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rua Conde de Bonfim 211/712, Rio de Janeiro, RJ, 20520-050, Brazil
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
- School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK
| | - Nelson Sena
- Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Aydano P Machado
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
- Brazilian Artificial Intelligence Networking in Medicine-BrAIN, Rio de Janeiro, Brazil
- Computing Institute, Federal University of Alagoas, Maceió, Brazil
- Brazilian Artificial Intelligence Networking in Medicine - BrAIN, Maceió, Brazil
| | - Paolo Vinciguerra
- Department of Biomedical Science, Humanitas University, Rozzano, Italy
- Eye Center, Humanitas Clinical and Research Center, Rozzano, Italy
| | - Riccardo Vinciguerra
- School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK
- Department of Ophthalmology, Humanitas San Pio X Hospital, Milan, Italy
| | - Renato Ambrósio
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rua Conde de Bonfim 211/712, Rio de Janeiro, RJ, 20520-050, Brazil.
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil.
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.
- Brazilian Artificial Intelligence Networking in Medicine-BrAIN, Rio de Janeiro, Brazil.
- Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil.
- Brazilian Artificial Intelligence Networking in Medicine - BrAIN, Maceió, Brazil.
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Thomasy SM, Leonard BC, Greiner MA, Skeie JM, Raghunathan VK. Squishy matters - Corneal mechanobiology in health and disease. Prog Retin Eye Res 2024; 99:101234. [PMID: 38176611 PMCID: PMC11193890 DOI: 10.1016/j.preteyeres.2023.101234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 12/22/2023] [Accepted: 12/27/2023] [Indexed: 01/06/2024]
Abstract
The cornea, as a dynamic and responsive tissue, constantly interacts with mechanical forces in order to maintain its structural integrity, barrier function, transparency and refractive power. Cells within the cornea sense and respond to various mechanical forces that fundamentally regulate their morphology and fate in development, homeostasis and pathophysiology. Corneal cells also dynamically regulate their extracellular matrix (ECM) with ensuing cell-ECM crosstalk as the matrix serves as a dynamic signaling reservoir providing biophysical and biochemical cues to corneal cells. Here we provide an overview of mechanotransduction signaling pathways then delve into the recent advances in corneal mechanobiology, focusing on the interplay between mechanical forces and responses of the corneal epithelial, stromal, and endothelial cells. We also identify species-specific differences in corneal biomechanics and mechanotransduction to facilitate identification of optimal animal models to study corneal wound healing, disease, and novel therapeutic interventions. Finally, we identify key knowledge gaps and therapeutic opportunities in corneal mechanobiology that are pressing for the research community to address especially pertinent within the domains of limbal stem cell deficiency, keratoconus and Fuchs' endothelial corneal dystrophy. By furthering our understanding corneal mechanobiology, we can contextualize discoveries regarding corneal diseases as well as innovative treatments for them.
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Affiliation(s)
- Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, United States; Department of Ophthalmology & Vision Science, School of Medicine, University of California - Davis, Davis, CA, United States; California National Primate Research Center, Davis, CA, United States.
| | - Brian C Leonard
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, United States; Department of Ophthalmology & Vision Science, School of Medicine, University of California - Davis, Davis, CA, United States
| | - Mark A Greiner
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, United States; Iowa Lions Eye Bank, Coralville, IA, United States
| | - Jessica M Skeie
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA, United States; Iowa Lions Eye Bank, Coralville, IA, United States
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Guedes J, Vilares-Morgado R, Brazuna R, Neto AC, Mora-Paez DJ, Salomão MQ, Faria-Correia F, Ambrósio R. Pressure-Induced Stromal Keratopathy after Surface Ablation Surgery. Case Rep Ophthalmol 2024; 15:532-541. [PMID: 39015239 PMCID: PMC11250257 DOI: 10.1159/000539701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 05/25/2024] [Indexed: 07/18/2024] Open
Abstract
Introduction The purpose of this clinical report was to describe an unprecedented case of bilateral pressure-induced stromal keratopathy (PISK) following corneal photorefractive keratectomy, associated with presumed herpetic keratitis, and to present tomographic and biomechanical findings before and after appropriate treatment. Case Presentation A 33-year-old male patient was referred to our clinic with suspected delayed corneal epithelial healing 3 weeks after an uncomplicated PRK. A central layer of corneal opacity with a presumed fluid-filled interface area was observed upon slit lamp biomicroscopy. Scheimpflug images from the Pentacam® revealed a hyperreflective area beneath the central cornea. Scheimpflug-based corneal tomography, biomechanical assessment using the Pentacam® AXL Wave, and the Corvis ST® were conducted. Goldmann applanation tonometry measured 23/13 mm Hg, while noncontact tonometry intraocular pressure measured with the Corvis ST® (Corvis ST IOPnct) was 40.5/43.5 mm Hg. Treatment with oral valacyclovir, combined with ocular hypotensive therapy, led to a significant reduction in IOP and improved corneal deformation parameters after 1 month. Conclusion Surgeons should be aware of the inaccuracy of Goldmann applanation tonometry in PISK, which can occur after LASIK or surface ablation.
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Affiliation(s)
- Jaime Guedes
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
| | - Rodrigo Vilares-Morgado
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Centro Hospitalar Universitário de S. João, Porto, Portugal
| | - Rodrigo Brazuna
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Alexandre Costa Neto
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | | | - Marcella Q. Salomão
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
| | - Fernando Faria-Correia
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- School of Medicine at the University of Minho, Braga, Portugal
| | - Renato Ambrósio
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
- Instituto de Olhos Renato Ambrósio and Visare, Rio de Janeiro, Brazil
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Shih PJ, Shih HJ, Wang IJ, Chang SW. The extraction and application of antisymmetric characteristics of the cornea during air-puff perturbations. Comput Biol Med 2024; 168:107804. [PMID: 38070205 DOI: 10.1016/j.compbiomed.2023.107804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 11/04/2023] [Accepted: 11/29/2023] [Indexed: 01/10/2024]
Abstract
BACKGROUND A non-contact tonometer is used to measure intraocular pressure, and studies have primarily relied on apex displacements to assess corneal properties. However, previous studies have overlooked the asymmetric characteristics of lateral corneal perturbations, leading to a gap in understanding of the lateral mechanical properties and its application. METHOD To investigate these lateral perturbations, we designed an experiment to sequentially record the corneal profiles when two consecutive air-puffs were applied at the center of the same cornea within a short period. Moreover, we used modal decomposition to decompose anterior surface profiles into symmetric and antisymmetric modes to comprehensively analyze the asymmetric characteristics. To extract mechanical properties, we utilized high-pass frequency analysis (>250 Hz) to filter out noise and errors. RESULTS Symmetric modes between the two consecutive air-puffs exhibited major similarities during vibration; however, antisymmetric modes exhibited minor differences in lateral perturbations of asymmetric vibration. The antisymmetric modes might be related to air-puff misalignment and mechanical properties. Through applying frequency analysis, the mechanical properties could be proven at high frequencies and misalignment shown at low frequencies. Furthermore, we compared the corneal vibration profiles of 259 healthy participants and 50 patients with keratoconus. Their properties showed that the antisymmetric modes of the keratoconus group exhibited a completely opposite direction of deformation compared to that in the healthy group. CONCLUSIONS Our proposed algorithm not only extracts antisymmetric characteristics but also offers valuable insights into decompose misalignment and mechanical properties of healthy and keratoconus corneas, presenting a new perspective for corneal biomechanics.
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Affiliation(s)
- Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
| | - Hua-Ju Shih
- Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan
| | - I-Jong Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
| | - Shu-Wen Chang
- Department of Ophthalmology, Far Eastern Memorial Hospital, New Taipei City, Taiwan.
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López-Muñoz A, López-Castaño I, Torres-Parejo Ú, García-Romera MC. A Corneal Biomechanical Study Measured with a Scheimpflug Dynamic Analyser in Soft Contact Lens Wearers. Life (Basel) 2023; 13:2313. [PMID: 38137914 PMCID: PMC10744429 DOI: 10.3390/life13122313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/01/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023] Open
Abstract
The aim of this study was to evaluate the biomechanical changes in the cornea after wearing soft contact lenses (CLs) in healthy myopic patients measured with a Corvis ST® (CST, Oculus Optikgeräte GmbH, Wetzlar, Germany) analyser. This prospective, cross-sectional, single-centre study was performed on twenty-two Caucasian patients aged between 19 and 24 years (20.64 ± 1.21 years) range. Five device-specific biomechanical parameters, the central corneal thickness (CCT), and biomechanically corrected intraocular pressure (bIOP) were measured prior to fitting and one month after CL wear. Differences between the means of the deflection amplitude ratio (DA Ratio) and the standard deviation of the DA Ratio (SD DA Ratio) pre- and post-CL wear were found to be significant (p value = 0.002 in both cases). Significant differences were found between pre- and post-CL wear values in CCT (p value = 0.013). For all other biomechanical measures, no significant differences were observed before and after treatment. A significant association was found between changes in bIOP and classification according to changes in Int. Radius (p value = 0.047) and SSI (p value = 0.026) standard deviations. The corneal biomechanical indices provided by CST demonstrate that the fitting of soft CLs is a safe optical compensation method for the stability of corneal stiffness. No significant differences were found pre- and post-CL wear in the assessment of bIOP.
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Affiliation(s)
- Alfredo López-Muñoz
- Department of Physics of Condensed Matter, Optics Area, Vision Sciences Research Group (CIVIUS), Pharmacy School, University of Seville, 41009 Seville, Spain; (I.L.-C.); (M.-C.G.-R.)
- Research & Development Department (Miranza Virgen de Luján®), Ophthalmology Center, 41011 Seville, Spain
| | - Isabel López-Castaño
- Department of Physics of Condensed Matter, Optics Area, Vision Sciences Research Group (CIVIUS), Pharmacy School, University of Seville, 41009 Seville, Spain; (I.L.-C.); (M.-C.G.-R.)
| | - Úrsula Torres-Parejo
- Department of Statistics and Operations Research, University of Grenade, 18071 Grenade, Spain;
| | - Marta-C. García-Romera
- Department of Physics of Condensed Matter, Optics Area, Vision Sciences Research Group (CIVIUS), Pharmacy School, University of Seville, 41009 Seville, Spain; (I.L.-C.); (M.-C.G.-R.)
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Huang X, Lin X, Yang Y, Yu J, Wang J, Li K, Wang Y, Savini G, Schiano-Lomoriello D, Zhou X, Huang J. Comparison of a New Scheimpflug Camera and Swept-Source Optical Coherence Tomographer for Measurements of Anterior Segment Parameters. Ophthalmol Ther 2023; 12:3187-3198. [PMID: 37747639 PMCID: PMC10640599 DOI: 10.1007/s40123-023-00813-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 08/31/2023] [Indexed: 09/26/2023] Open
Abstract
INTRODUCTION This study evaluated the differences and agreement between a new Scheimpflug camera (Scansys) and a swept-source anterior segment optical coherence tomographer (CASIA 2) for measurements of the anterior segment of the eye in normal subjects. METHODS This prospective study included 84 eyes from 84 normal adult subjects who underwent three consecutive measurements with the Scansys and the CASIA 2 in random order. The mean keratometry (Km), astigmatism magnitude (AST), J0, and J45 vectors for both anterior and posterior corneal surfaces, central corneal thickness (CCT), thinnest corneal thickness (TCT), and anterior chamber depth (ACD) were obtained by both devices. The difference between these two devices was assessed using paired t test and violin plots. Bland-Altman plots and 95% limits of agreement (LoAs) were used to evaluate agreement. RESULTS No statistically significant differences between the two devices were found for the anterior AST, anterior J45, and posterior J45 (P > 0.05). The remaining parameters were statistically significant (P ≤ 0.05), but the differences not clinically significant. The violin plots showed that the distribution and probability density of the measured parameters were similar for both devices. Bland-Altman plots revealed high agreement for the measured parameters between the Scansys and CASIA 2, with narrow 95% LoAs. CONCLUSIONS In terms of assessing parameters for the anterior segment, our study indicated that Scansys and CASIA 2 generally showed significant agreement. The two devices used in this study's assessment of all the parameters can be used interchangeably in refractive analysis.
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Affiliation(s)
- Xiaomin Huang
- Eye Institute and Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, No.19 Baoqing Road, Xuhui District, Shanghai, 200031, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Key Laboratory of Myopia, NHC Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, Shanghai, China
| | - Xuanqiao Lin
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yizhou Yang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jinjin Yu
- Eye Institute and Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, No.19 Baoqing Road, Xuhui District, Shanghai, 200031, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Key Laboratory of Myopia, NHC Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, Shanghai, China
| | - Jiacheng Wang
- Eye Institute and Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, No.19 Baoqing Road, Xuhui District, Shanghai, 200031, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Key Laboratory of Myopia, NHC Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, Shanghai, China
| | - Kexin Li
- Eye Institute and Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, No.19 Baoqing Road, Xuhui District, Shanghai, 200031, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Key Laboratory of Myopia, NHC Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, Shanghai, China
| | - Yiran Wang
- Eye Institute and Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, No.19 Baoqing Road, Xuhui District, Shanghai, 200031, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Key Laboratory of Myopia, NHC Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, Shanghai, China
| | | | | | - Xingtao Zhou
- Eye Institute and Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, No.19 Baoqing Road, Xuhui District, Shanghai, 200031, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Key Laboratory of Myopia, NHC Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, Shanghai, China
| | - Jinhai Huang
- Eye Institute and Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, No.19 Baoqing Road, Xuhui District, Shanghai, 200031, China.
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China.
- Key Laboratory of Myopia, NHC Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, Shanghai, China.
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Vinciguerra R, Cancian G, Ambrósio R, Elsheikh A, Eliasy A, Lopes B, Vinciguerra P. Assessment of the specificity of corvis biomechanical index-laser vision correction (CBI-LVC) in stable corneas after phototherapeutic keratectomy. Int Ophthalmol 2023; 43:4289-4295. [PMID: 37644351 DOI: 10.1007/s10792-023-02840-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 07/27/2023] [Indexed: 08/31/2023]
Abstract
PURPOSE The Corvis Biomechanical Index-Laser Vision Correction (CBI-LVC) is a biomechanical index to detect ectasia in post-refractive surgery patients (PRK, LASIK, SMILE). This study aims to evaluate the distribution of the CBI-LVC in stable patients who underwent Phototherapeutic Keratectomy (PTK) compared to PRK patients. METHODS Patients who underwent PRK and PTK performed between 2000 and 2018 in Humanitas Research Hospital, Rozzano, Milan, Italy and remained stable for at least four years post-surgery were included. All eyes were examined with the Corvis ST (Oculus, Germany), whose output allows the calculation of the CBI-LVC. The distribution and specificity of the CBI-LVC in the two populations were estimated using a Wilcoxon Mann-Whitney test and compared. RESULTS 175 eyes of 148 patients were included (85 eyes of 50 PTK patients and 90 eyes of 90 PRK patients). The distribution of CBI-LVC in the two groups showed a minor difference, with a median value in PRK patients of 0.000 (95% CI 0.000; 0.002) and 0.008 (95% CI 0.000; 0.037) in PTK patients (Mann-Whitney U test p = 0.023). The statistical analysis showed that the CBI-LVC provided a specificity of 92.22% in the PRK group, while in the PTK group it was 82.35%. Nevertheless, this difference was not statistically significant (Chi-squared test with Yates, p = 0.080). CONCLUSION CBI-LVC provided similar specificity in stable PTK patients compared to those who underwent PRK. These results suggest that the CBI-LVC could be a useful tool to aid corneal surgeons in managing PTK patients.
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Affiliation(s)
- Riccardo Vinciguerra
- Humanitas San Pio X Hospital, Via Francesco Nava 31, Milan, Italy.
- The School of Engineering, University of Liverpool, Liverpool, UK.
| | - Giuseppe Cancian
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090, Pieve Emanuele, Milan, Italy
| | - Renato Ambrósio
- Department of Ophthalmology, The Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
- Department of Ophthalmology, The Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Ahmed Elsheikh
- The School of Engineering, University of Liverpool, Liverpool, UK
- Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, 100083, China
- NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Ashkan Eliasy
- The School of Engineering, University of Liverpool, Liverpool, UK
| | - Bernardo Lopes
- The School of Engineering, University of Liverpool, Liverpool, UK
| | - Paolo Vinciguerra
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090, Pieve Emanuele, Milan, Italy
- Humanitas Clinical and Research Center-IRCCS, Via Manzoni 56, 20089, Rozzano, Mi, Italy
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Chen X, Tan Z, Huo Y, Song J, Xu Q, Yang C, Jhanji V, Li J, Hou J, Zou H, Ali Khan G, Alzogool M, Wang R, Wang Y. Localized Corneal Biomechanical Alteration Detected In Early Keratoconus Based on Corneal Deformation Using Artificial Intelligence. Asia Pac J Ophthalmol (Phila) 2023; 12:574-581. [PMID: 37973045 DOI: 10.1097/apo.0000000000000644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 09/27/2023] [Indexed: 11/19/2023] Open
Abstract
PURPOSE This study aimed to develop a novel method to diagnose early keratoconus by detecting localized corneal biomechanical changes based on dynamic deformation videos using machine learning. DESIGN Diagnostic research study. METHODS We included 917 corneal videos from the Tianjin Eye Hospital (Tianjin, China) and Shanxi Eye Hospital (Xi'an, China) from February 6, 2015, to August 25, 2022. Scheimpflug technology was used to obtain dynamic deformation videos under forced puffs of air. Fourteen new pixel-level biomechanical parameters were calculated based on a spline curve equation fitting by 115,200-pixel points from the corneal contour extracted from videos to characterize localized biomechanics. An ensemble learning model was developed, external validation was performed, and the diagnostic performance was compared with that of existing clinical diagnostic indices. The performance of the developed machine learning model was evaluated using precision, recall, F1 score, and the area under the receiver operating characteristic curve. RESULTS The ensemble learning model successfully diagnosed early keratoconus (area under the curve = 0.9997) with 95.73% precision, 95.61% recall, and 95.50% F1 score in the sample set (n=802). External validation on an independent dataset (n=115) achieved 91.38% precision, 92.11% recall, and 91.18% F1 score. Diagnostic accuracy was significantly better than that of existing clinical diagnostic indices (from 86.28% to 93.36%, all P <0.01). CONCLUSIONS Localized corneal biomechanical changes detected using dynamic deformation videos combined with machine learning algorithms were useful for diagnosing early keratoconus. Focusing on localized biomechanical changes may guide ophthalmologists, aiding the timely diagnosis of early keratoconus and benefiting the patient's vision.
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Affiliation(s)
- Xuan Chen
- School of Medicine, Nankai University, Tianjin, China
| | - Zuoping Tan
- Wenzhou University of Technology, Wenzhou, Zhejiang, China
| | - Yan Huo
- School of Medicine, Nankai University, Tianjin, China
| | - Jiaxin Song
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Qiang Xu
- Wenzhou University of Technology, Wenzhou, Zhejiang, China
| | - Can Yang
- Wenzhou University of Technology, Wenzhou, Zhejiang, China
| | - Vishal Jhanji
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Jing Li
- Shanxi Eye Hospital, Xi'an People's Hospital, Xi'an, China
| | - Jie Hou
- Jinan Mingshui Eye Hospital, Ji'nan, Shandong, China
| | - Haohan Zou
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Gauhar Ali Khan
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | | | - Riwei Wang
- Wenzhou University of Technology, Wenzhou, Zhejiang, China
| | - Yan Wang
- School of Medicine, Nankai University, Tianjin, China
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Tianjin, China
- Nankai Eye Institute, Nankai University, Tianjin, China
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11
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Cao H, Jhanji V, Wang Y. Relationship between postoperative residual refractive error and preoperative corneal stiffness in small-incision lenticule extraction. J Cataract Refract Surg 2023; 49:942-948. [PMID: 37379041 DOI: 10.1097/j.jcrs.0000000000001250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 06/21/2023] [Indexed: 06/29/2023]
Abstract
PURPOSE To explore the relationship between postoperative residual refractive error and preoperative corneal stiffness after small-incision lenticule extraction (SMILE). SETTING Hospital clinic. DESIGN Retrospective cohort study. METHODS Corneal stiffness was evaluated using the stress-strain index (SSI). Associations between postoperative spherical equivalent (SE) and corneal stiffness were determined using longitudinal regression analysis after adjustment for sex, age, preoperative SE, and other variables. The cohort was divided into halves to compare risk ratios for residual refraction in corneas with different SSI values. Low SSI values were defined as having less-stiff corneas and others as having stiffer corneas. RESULTS 287 patients (287 eyes) were included. Greater undercorrection was found in less-stiff corneas across all follow-up timepoints (less-stiff corneas: 1 day: -0.36 ± 0.45 diopters [D], 1 month: -0.22 ± 0.36 D, and 3 months: -0.13 ± 0.15 D; stiffer corneas: -0.22 ± 0.37 D, -0.14 ± 0.35 D, and -0.05 ± 0.11 D, respectively). Postoperative refraction exhibited a mean 0.05 D undercorrection for every 0.1-unit decrease in the SSI after adjustment for variables. The SSI accounted for nearly 10% of the variance in refractive outcomes. Less-stiff corneas increased the risk ratio of postoperative absolute SE >0 D and ≥0.25 D by 2.242 (95% CI, 1.334-3.768) and 3.023 (95% CI, 1.466-6.233), respectively, compared with stiffer corneas. CONCLUSIONS Postoperative residual refractive error was associated with preoperative corneal stiffness. Patients with less-stiff corneas had a 2- to 3-fold increased risk of residual refractive error after SMILE. Preoperative analysis of corneal stiffness can help modify nomogram algorithms of surgery and improve the predictability of refractive outcomes.
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Affiliation(s)
- Huazheng Cao
- From the School of Medicine, Nankai University, Tianjin, China (Cao); Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (Jhanji); Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Tianjin, China (Wang); Nankai Eye Institute, Nankai University, Tianjin, China (Wang)
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12
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Vinciguerra R, Ambrosio R, Wang Y, Zhang F, Zhou X, Bai J, Yu K, Chen S, Fang X, Vinciguerra P. Detection of Keratoconus With a New Corvis Biomechanical Index Optimized for Chinese Populations. Am J Ophthalmol 2023; 252:182-187. [PMID: 37059320 DOI: 10.1016/j.ajo.2023.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 04/01/2023] [Accepted: 04/05/2023] [Indexed: 04/16/2023]
Abstract
PURPOSE The aim of this study was to introduce an optimized version of the Corvis Biomechanical Index for Chinese populations (cCBI). DESIGN Retrospective, multicenter clinical validity enhancement study. METHODS Patients were included from 7 clinics in Beijing, Shenyang, Guangzhou, Shanghai, Wenzhou, Chongqing, and Tianjin, China. Logistic regression was used to optimize the values of the constants of the CBI, based on database 1 as the development dataset (6 of 7 clinics), to create a new version of the index named cCBI. The factors of the CBI (A1Velocity, ARTh, Stiffness Parameter-A, DARatio2mm, and Inverse Integrated Radius) and the cutoff value were kept the same (0.5). With the formation of cCBI determined, it was validated on database 2 (1 of the 7 clinics). RESULTS Two thousand four hundred seventy-three patients (healthy and keratoconus) were included. In database 2, the area under the curve of the cCBI was 0.985 with 93.4% specificity and 95.5% sensitivity. In the same dataset, the original CBI produced an area under the curve of 0.978 with 68.1% specificity and 97.7% sensitivity. There was a statistically significant difference between the receiver operating characteristic curve of cCBI and CBI (De Long P = .0009) CONCLUSION: The new cCBI for Chinese patients was shown to be statistically significantly better when compared with CBI to separate healthy from keratoconic eyes. The presence of an external validation dataset confirms this finding and suggests the use of cCBI in everyday clinical practice to aid in the diagnosis of keratoconus in patients who are of Chinese ethnicity.
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Affiliation(s)
| | - Renato Ambrosio
- Department of Ophthalmology (R.A.), the Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Yan Wang
- Tianjin Eye Hospital (Y.W.), Tianjin Key Laboratory of Ophthalmology and Visual Science, Nankai University Affiliated Eye Hospital; Clinical College of Ophthalmology (Y.W.), Tianjin Medical University, Tianjin, China
| | - Fengju Zhang
- Beijing Tongren Eye Center (F.Z.), Beijing Tongren Hospital, Beijing Ophthalmology and Visual Sciences Key Lab, Capital Medical University, Beijing, China
| | - Xingtao Zhou
- Eye and ENT Hospital of Fudan University (X.Z.), Shanghai, China
| | - Ji Bai
- BAI JI Ophthalmology (J.B.), Chongqing, China
| | - Keming Yu
- Zhongshan Ophthalmic Center (K.Y.), Sun Yat-Sen University, Guangzhou, China
| | - Shihao Chen
- Eye Hospital (S.C.), Wenzhou Medical University, Zhejiang, China
| | - Xuejun Fang
- Shenyang Aier Eye Hospital (X.F.), Shenyang, China
| | - Paolo Vinciguerra
- Humanitas University, Department of Biomedical Sciences, Via Rita Levi Montalcini 4, 20090 Pieve Emanuele, Milan, Italy; IRCCS Humanitas Research Hospital, via Manzoni 56, 20089 Rozzano, Milan, Italy
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13
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Pedrotti E, Bonacci E, Fasolo A, Longo R, Pastore G, Vinciguerra R, Vinciguerra P, Marchini G. Corneal Biomechanical Evaluation After Meniscus-Shaped Stromal Lenticule Addition Keratoplasty (MS-SLAK) for Keratoconus. J Refract Surg 2023; 39:499-504. [PMID: 37449508 DOI: 10.3928/1081597x-20230523-02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
PURPOSE To evaluate corneal biomechanical changes after meniscus-shaped stromal lenticule addition keratoplasty (MS-SLAK) performed for the treatment of keratoconus. METHODS This interventional study included patients affected by advanced keratoconus (stage III and IV) who underwent examination with a dynamic Scheimpflug analyzer and non-contact tonometer (Corvis ST; Oculus Optikgeräte GmbH) at baseline and 12 months after MS-SLAK. The biomechanical parameters evaluated in this study were integrated inverse radius (1/R), deformation amplitude ratio (DA ratio), stiffness parameter at first applanation (SP-A1), biomechanical intraocular pressure (bIOP), central corneal thickness (CCT), and stress-strain index (SSI). RESULTS Sixteen patients were enrolled in the study. The analysis was ultimately conducted on 15 patients. Comparative analyses showed an increase in corneal stiffness as demonstrated by a rise in SSI (P < .0001) and SP-A1 (P < .0001) and a decrease in DA ratio (P < .0001) and 1/R (P = .01). A significant increase in CCT was found (P < .0001). No statistically significant modification was found for bIOP (P = .43). CONCLUSIONS The corneal biomechanical analyses evaluated by the Corvis ST showed that MS-SLAK for advanced keratoconus is able to increase corneal overall stiffness. This result is explained by the significant increase in thickness induced by MS-SLAK. [J Refract Surg. 2023;39(7):499-504.].
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Flockerzi E, Xanthopoulou K, Munteanu C, Daas L, Langenbucher A, Seitz B. The Biomechanical E-Staging: In Vivo Biomechanics in Keratoconus. Klin Monbl Augenheilkd 2023; 240:761-773. [PMID: 37348512 DOI: 10.1055/a-2079-1740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2023]
Abstract
Belin's ABCD keratoconus classification system allows keratoconus staging based on the criteria of anterior (A) and posterior (B) corneal curvature, thinnest corneal thickness (C), and best spectacle-corrected visual acuity (D). These parameters also provide a progression assessment, but do not take corneal biomechanics into account. The analysis of corneal biomechanics by the Corvis ST (Oculus, Wetzlar, Germany) allows for separation of healthy and keratoconus corneas, based on the Corvis Biomechanical Index (CBI) and the Tomographic Biomechanical Index (TBI). As Corvis ST measurements are highly reliable and are independent of keratoconus severity, a biomechanical parameter was developed for keratoconus corneas based on the linear term of the CBI. This provides biomechanical keratoconus staging. The Corvis Biomechanical Factor (CBiF) is the basis for the introduction of the biomechanical E-staging, which augments the ABCD classification to the ABCDE classification, thus including the cornerstone of corneal biomechanics. This article highlights strengths and limitations of the ABCDE classification. "Unilateral keratoconus" supposedly turns out to be mostly a snapshot of a highly asymmetric keratectasia. Regular astigmatism is sometimes an important differential diagnosis to keratectasia and may be difficult to differentiate from it. Furthermore, the use of the biomechanical E-staging in daily practice for progression assessment of keratoconus and after its treatment by corneal cross-linking or implantation of intracorneal ring segments will be demonstrated and discussed.
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Affiliation(s)
- Elias Flockerzi
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg, Deutschland
| | - Kassandra Xanthopoulou
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg, Deutschland
| | - Cristian Munteanu
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg, Deutschland
| | - Loay Daas
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg, Deutschland
| | - Achim Langenbucher
- Institut für Experimentelle Ophthalmologie, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg, Deutschland
| | - Berthold Seitz
- Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg, Deutschland
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15
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Assessment of the corneal biomechanical features of granular corneal dystrophy type 2 using dynamic ultra-high-speed Scheimpflug imaging. Graefes Arch Clin Exp Ophthalmol 2023; 261:761-767. [PMID: 36178505 DOI: 10.1007/s00417-022-05847-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 11/04/2022] Open
Abstract
PURPOSE To evaluate the corneal biomechanical features of eyes with granular corneal dystrophy type 2 (GCD2) by analyzing corneal biomechanical indices obtained using a Corvis ST (CST) dynamic ultra-high-speed Scheimpflug imaging device. METHODS In this retrospective case-control study, 35 CST parameters were compared in normal eyes (control) and eyes of patients with GCD2 treated at Osaka University Hospital, Osaka, Japan. The parameters included the Corvis Biomechanical Index (CBI), which is important in differentiating eyes with keratoconus from normal eyes. We measured the deposition rates of lesions in the central 7-mm region of the eye and assessed the correlation between the deposition rate and the CBI. RESULTS Twenty-one eyes with GCD2 and 23 control eyes were analyzed. Eyes with GCD2 showed significantly less corneal stiffness in 15 CST parameters than did control eyes. In particular, the CBI was remarkably higher in eyes with GCD2 than in control eyes (P = 0.000006). Additionally, the deposition rate and the CBI were positively correlated. CONCLUSIONS GCD2 eyes had softer corneas than did control eyes in most biomechanical CST parameters, and one of the parameters (the CBI) was linked to the rate of deposited lesions. Since IOP may be underestimated in GCD2 eyes, management should be especially careful in GCD2 cases complicated by glaucoma.
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16
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Esporcatte LPG, Salomão MQ, Lopes BT, Sena N, Ferreira É, Filho JBRF, Machado AP, Ambrósio R. Biomechanics in Keratoconus Diagnosis. Curr Eye Res 2023; 48:130-136. [PMID: 35184637 DOI: 10.1080/02713683.2022.2041042] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Purpose: To prospectively review the importance of biomechanical assessment in the screening, diagnosis, prognosis, individualized planning, and clinical follow-up for ectatic corneal diseases.Methods: We demonstrate two commercially available devices to assess the corneal biomechanics in vivo, the Ocular Response Analyzer (ORA, Reichester, NY, USA) and the Corvis ST (Oculus, Wetzlar, Germany). Novel devices have been demonstrated to provide in vivo biomechanical measurements, including Brillouin optical microscopy and OCT elastography. Conclusion: The integration of biomechanical data and other data from multimodal refractive imaging using artificial intelligence demonstrated the ability to enhance accuracy in diagnosing ectatic corneal diseases.
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Affiliation(s)
- Louise Pellegrino G Esporcatte
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.,Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil.,Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | - Marcella Q Salomão
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.,Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil.,Brazilian Artificial Intelligence Networking in Medicine - BrAIN, Rio de Janeiro and Maceió, Brazil.,Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.,Instituto Benjamin Constant, Rio de Janeiro, Brazil
| | - Bernardo T Lopes
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.,School of Engineering, University of Liverpool, Liverpool, UK
| | - Nelson Sena
- Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Érica Ferreira
- Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Joao Batista R F Filho
- Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Aydano P Machado
- Brazilian Artificial Intelligence Networking in Medicine - BrAIN, Rio de Janeiro and Maceió, Brazil.,Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.,Computing Institute, Federal University of Alagoas, Maceió, Brazil
| | - Renato Ambrósio
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.,Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil.,Brazilian Artificial Intelligence Networking in Medicine - BrAIN, Rio de Janeiro and Maceió, Brazil.,Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.,Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
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17
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Abstract
PURPOSE The relevance of corneal biomechanics and the importance of including it in the clinical assessment of corneal ectasias are being increasingly recognized. The connection between corneal ultrastructure, biomechanical properties, and optical function is exemplified by a condition like keratoconus. Biomechanical instability is seen as the underlying basis for the secondary morphological changes in the cornea. Asymmetric biomechanical weakening is believed to drive progressive corneal steepening and thinning. Biomechanical strengthening is the principle of collagen crosslinking that has been shown to effectively arrest progression of the keratoconus. Corneal biomechanics has therefore ignited the interest of researchers and clinicians alike and has given us new insights into the cause and course of the disease. This article is an overview of the extensive work published, predominantly in the last two decades, on the biomechanical aspect of keratoconus. METHODS Published articles on corneal biomechanics in the specific context of keratoconus were reviewed, based on an electronic search using PubMed, Elsevier, and Science Direct. The search terms used included "Corneal Biomechanics," "Mechanical properties of the cornea," "Corneal ultrastructure," "Corneal Collagen," and "Keratoconus". Articles pertaining to refractive surgery, keratoplasty, collagen crosslinking, or intrastromal rings were excluded. RESULTS The electronic search revealed more than 500 articles, from which 80 were chosen for this article. CONCLUSIONS The structural and organizational pattern of the corneal stroma determines its mechanical properties and are responsible for the maintenance of the normal shape and function of the cornea. Changes in the ultrastructure are responsible for the biomechanical instability that leads to corneal ectasia. As non-invasive methods for evaluating corneal biomechanics in vivo evolve, our ability to diagnose subclinical keratoconus will improve, allowing identification of patients at risk to develop ectasia and to allow early treatment to arrest progression of the disease.
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Affiliation(s)
- Prema Padmanabhan
- Department of Cornea and Refractive Surgery, Medical Research Foundation, Sankara Nethralaya, Chennai, India
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, UK.,Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China.,NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
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18
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Lv X, Zhang F, Song Y, Zhai C, Guo N, Lai L, Xu Y. Corneal biomechanical characteristics following small incision lenticule extraction for myopia and astigmatism with 3 different cap thicknesses. BMC Ophthalmol 2023; 23:42. [PMID: 36717828 PMCID: PMC9885585 DOI: 10.1186/s12886-023-02786-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 01/16/2023] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND The design of cap thickness for small incision lenticule extraction (SMILE) plays a role in post-laser vision correction (post-LVC) corneal biomechanics. This study aimed to compare the corneal biomechanical characteristics following SMILE with different cap thicknesses of 110 μm, 120 μm, and 130 μm for myopia and myopic astigmatism correction. METHODS Seventy-five patients (146 eyes) who underwent SMILE with designed cap thickness of 110 μm, 120 μm, and 130 μm were recruited at the Eye Center of Beijing Tongren Hospital between August 2020 and November 2021. Visual acuity, refraction, and corneal biomechanical parameters were measured preoperatively, 1 week and 1, 3, 6 months postoperatively. One-way analysis of variances (ANOVA) with Bonferroni correction or Kruskal-Wallis test was performed to compare the parameters among different groups. Repeated-measures analysis of variance with Bonferroni correction or Friedman test was applied for comparing the parameters within different follow-up times. RESULTS Uncorrected distance visual acuity of 110-μm group was better only at 1-week and 1-month postoperatively (P = 0.012, 0.037). There were no significant differences in spherical equivalent, nor in Corvis biomechanical index-laser vision correction (CBI-LVC). All the parameters reached stability at 3-month postoperatively. Integrated radius (IR) and deformation amplitude ratio 2 mm (DA ratio 2 mm) in 120-μm and 130-μm groups were higher than 110-μm group at 1-month postoperatively (P = 0.019, 0.002). So was Ambrósio relational thickness (ARTh) at 6-month postoperatively (P = 0.011). Stiffness parameter at applanation A1 (SP-A1), stress-strain index (SSI), biomechanically corrected intraocular pressure (bIOP) and central corneal thickness (CCT) were highest in 130-μm group, followed by 120-μm group, then 110-μm group at 3-month (P<0.001, P = 0.030, P = 0.027, P = 0.008) and 6-month (P<0.001, P = 0.002, P = 0.0023, P = 0.001) postoperatively. CONCLUSIONS The corneal stiffness following SMILE was greatest with 130-μm cap, followed by 120-μm cap, then 110-μm cap. 130-μm cap might have advantages in terms of corneal biomechanics and retreatment option. The SMILE-designed protocol should be customized in practice.
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Affiliation(s)
- Xiaotong Lv
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Fengju Zhang
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Yanzheng Song
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Changbin Zhai
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Ning Guo
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Lingbo Lai
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
| | - Yushan Xu
- grid.414373.60000 0004 1758 1243Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, No 1, Dongjiaominxiang Street, Dongcheng District, Beijing, 100730 China
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19
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Ramm L, Herber R, Lorenz G, Jasper CS, Pillunat LE, Pillunat KR. Evaluation of corneal biomechanical properties using the ocular response analyzer and the dynamic Scheimpflug-Analyzer Corvis ST in high pressure and normal pressure open-angle glaucoma patients. PLoS One 2023; 18:e0281017. [PMID: 36701409 PMCID: PMC9879466 DOI: 10.1371/journal.pone.0281017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 01/12/2023] [Indexed: 01/27/2023] Open
Abstract
PURPOSE To characterize differences in corneal biomechanics in high (HPG) and normal pressure (NPG) primary open-angle glaucoma, and its association to disease severity. METHODS Corneal biomechanical properties were measured using the Ocular Response Analyzer (ORA) and the dynamic Scheimpflug-Analyzer Corvis ST (CST). Disease severity was functionally assessed by automated perimetry (Humphrey field analyzer) and structurally with the Heidelberg Retina Tomograph. To avoid a possible falsification by intraocular pressure, central corneal thickness and age, which strongly influence ORA and CST measurements, group matching was performed. Linear mixed models and generalized estimating equations were used to consider inter-eye correlation. RESULTS Following group matching, 60 eyes of 38 HPG and 103 eyes of 60 NPG patients were included. ORA measurement revealed a higher CRF in HPG than in NPG (P < 0.001). Additionally, the CST parameter integrated radius (P < 0.001) was significantly different between HPG and NPG. The parameter SSI (P < 0.001) representing corneal stiffness was higher in HPG than in NPG. Furthermore, regression analysis revealed associations between biomechanical parameters and indicators of disease severity. In HPG, SSI correlated to RNFL thickness. In NPG, dependencies between biomechanical readings and rim area, MD, and PSD were shown. CONCLUSION Significant differences in corneal biomechanical properties were detectable between HPG and NPG patients which might indicate different pathophysiological mechanisms underlying in both entities. Moreover, biomechanical parameters correlated to functional and structural indices of diseases severity. A reduced corneal deformation measured by dynamic methods was associated to advanced glaucomatous damage.
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Affiliation(s)
- Lisa Ramm
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Robert Herber
- Faculty of Medicine Carl Gustav Carus, Department of Ophthalmology, TU Dresden, Dresden, Germany
- * E-mail:
| | - Georg Lorenz
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Carolin S. Jasper
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Lutz E. Pillunat
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Karin R. Pillunat
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
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20
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Enhanced Diagnostics for Corneal Ectatic Diseases: The Whats, the Whys, and the Hows. Diagnostics (Basel) 2022; 12:diagnostics12123027. [PMID: 36553038 PMCID: PMC9776904 DOI: 10.3390/diagnostics12123027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 11/27/2022] [Accepted: 11/30/2022] [Indexed: 12/07/2022] Open
Abstract
There are different fundamental diagnostic strategies for patients with ectatic corneal diseases (ECDs): screening, confirmation of the diagnosis, classification of the type of ECD, severity staging, prognostic assessment, and clinical follow-up. The conscious application of such strategies enables individualized treatments. The need for improved diagnostics of ECD is related to the advent of therapeutic refractive procedures that are considered prior to keratoplasty. Among such less invasive procedures, we include corneal crosslinking, customized ablations, and intracorneal ring segment implantation. Besides the paradigm shift in managing patients with ECD, enhancing the sensitivity to detect very mild forms of disease, and characterizing the inherent susceptibility for ectasia progression, became relevant for identifying patients at higher risk for progressive iatrogenic ectasia after laser vision correction (LVC). Moreover, the hypothesis that mild keratoconus is a risk factor for delivering a baby with Down's syndrome potentially augments the relevance of the diagnostics of ECD. Multimodal refractive imaging involves different technologies, including Placido-disk corneal topography, Scheimpflug 3-D tomography, segmental or layered tomography with layered epithelial thickness using OCT (optical coherence tomography), and digital very high-frequency ultrasound (VHF-US), and ocular wavefront. Corneal biomechanical assessments and genetic and molecular biology tests have translated to clinical measurements. Artificial intelligence allows for the integration of a plethora of clinical data and has proven its relevance in facilitating clinical decisions, allowing personalized or individualized treatments.
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21
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Reliability analysis of successive Corvis ST® measurements in keratoconus 2 years after accelerated corneal crosslinking compared to untreated keratoconus corneas. Graefes Arch Clin Exp Ophthalmol 2022; 261:1055-1061. [PMID: 36305911 PMCID: PMC10049946 DOI: 10.1007/s00417-022-05881-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 10/12/2022] [Accepted: 10/20/2022] [Indexed: 11/04/2022] Open
Abstract
Abstract
Purpose
To assess the reliability of successive Corvis ST® measurements (CST, Oculus, Wetzlar, Germany) in keratoconus (KC) ≥ 2 years after accelerated corneal crosslinking (9 mW/cm2, 10 min, 5.4 J/cm2) compared to untreated KC corneas.
Methods
Three successive CST measurements per eye were performed in ≥ 2 years after CXL (CXLG, n = 20 corneas of 16 patients) and a control group consisting of non-operated, ABC-stage-matched KC corneas according to Belin’s ABCD KC grading (controls, n = 20 corneas, 20 patients). Main outcome measures included maximal keratometry (Kmax), the Belin/Ambrósio-Enhanced-Ectasia-Deviation-Index BAD-D; the biomechanical parameters A1 velocity, deformation amplitude (DA) ratio 2 mm, Ambrósio relational thickness to the horizontal profile (ARTh), integrated radius, stiffness parameter A1 (SP-A1), and the Corvis Biomechanical Factor (CBiF, the linearized term of the Corvis Biomechanical Index). Mean values, standard deviations, and Cronbach’s alpha (CA) were calculated.
Results
Both groups were tomographically comparable (BAD: 11.5 ± 4.7|11.2 ± 3.6, p = 0.682, Kmax: 60.5 ± 7.2|60.7 ± 7.7, p = 0.868 for controls|CXLG, paired t-test). A1 velocity (mean ± SD: 0.176 ± 0.02|0.183 ± 0.02, p = 0.090, CA: 0.960|0.960), DA ratio 2 mm (6.04 ± 1.13|6.14 ± 1.03, p = 0.490, CA: 0.967|0.967), integrated radius (12.08 ± 2.5|12.42 ± 1.9, p = 0.450, CA: 0.976|0.976), and CBiF (4.62 ± 0.6|4.62 ± 0.4, p = 0.830, CA: 0.965|0.965) were also comparable (controls|CXLG). ARTh was significantly higher in controls (177.1 ± 59, CA: 0.993) than after CXL (155.21 ± 65, p = 0.0062, CA: 0.993) and SP-A1 was significantly higher after CXL (59.2 ± 13, CA: 0.912) than in controls (52.2 ± 16, p = 0.0018, CA: 0.912).
Conclusion
ARTh and SP-A1 differed significantly between controls and CXLG. Biomechanical measurements were generally of excellent reliability in both groups. CXL seems to affect biomechanical measurements of human corneas over more than 2 years.
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22
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Esporcatte LPG, Salomão MQ, Junior NS, Machado AP, Ferreira É, Loureiro T, Junior RA. Corneal biomechanics for corneal ectasia: Update. Saudi J Ophthalmol 2022; 36:17-24. [PMID: 35971484 PMCID: PMC9375464 DOI: 10.4103/sjopt.sjopt_192_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/23/2021] [Accepted: 11/18/2021] [Indexed: 11/09/2022] Open
Abstract
Knowledge of biomechanical principles has been applied in several clinical conditions, including correcting intraocular pressure measurements, planning and following corneal treatments, and even allowing an enhanced ectasia risk evaluation in refractive procedures. The investigation of corneal biomechanics in keratoconus (KC) and other ectatic diseases takes place in several steps, including screening ectasia susceptibility, the diagnostic confirmation and staging of the disease, and also clinical characterization. More recently, investigators have found that the integration of biomechanical and tomographic data through artificial intelligence algorithms helps to elucidate the etiology of KC and ectatic corneal diseases, which may open the door for individualized or personalized medical treatments in the near future. The aim of this article is to provide an update on corneal biomechanics in the screening, diagnosis, staging, prognosis, and treatment of KC.
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Affiliation(s)
- Louise P. G. Esporcatte
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Brazil,Renato Ambrosio Eye Institute, Rio de Janeiro, Brazil,Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | - Marcella Q. Salomão
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Brazil,Renato Ambrosio Eye Institute, Rio de Janeiro, Brazil,Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil,Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro and Maceió, Brazil,Benjamin Constant Institute, Rio de Janeiro, Brazil
| | - Nelson S. Junior
- Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Aydano P. Machado
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil,Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro and Maceió, Brazil,Department of Computer Sciences, Federal University of Alagoas, Maceió, Brazil
| | - Érica Ferreira
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Brazil,Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Tomás Loureiro
- Department of Ophthalmology, Garcia de Orta Hospital, Almada, Portugal
| | - Renato A. Junior
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Brazil,Renato Ambrosio Eye Institute, Rio de Janeiro, Brazil,Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil,Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro and Maceió, Brazil,Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil,Address for correspondence: Dr. Renato A. Junior, Rua Conde de Bonfim, 211/712, 20520-050, Rio de Janeiro, RJ, Brazil. E-mail:
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23
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Vinciguerra R, Herber R, Wang Y, Zhang F, Zhou X, Bai J, Yu K, Chen S, Fang X, Raiskup F, Vinciguerra P. Corneal Biomechanics Differences Between Chinese and Caucasian Healthy Subjects. Front Med (Lausanne) 2022; 9:834663. [PMID: 35280913 PMCID: PMC8914014 DOI: 10.3389/fmed.2022.834663] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/31/2022] [Indexed: 11/16/2022] Open
Abstract
Purpose The aim of this study was to evaluate the difference between Caucasian and Chinese healthy subjects with regards to Corvis ST dynamic corneal response parameters (DCRs). Methods Two thousand eight hundred and eighty-nine healthy Caucasian and Chinese subjects were included in this multicenter retrospective study. Subsequently, Chinese eyes were matched to Caucasians by age, intraocular pressure (IOP), and Corneal Thickness (CCT) using a case-control matching algorithm. The DCRs assessed were Deformation Amplitude (DA) Applanation 1 velocity (A1v), integrated radius (1/R), deformation amplitude ratio (DAratio), stiffness parameter at applanation 1 (SPA1), ARTh (Ambrósio's Relational Thickness to the horizontal profile), and the novel Stress Strain Index (SSI). Results After age-, CCT-, and IOP- matching, 503 Chinese were assigned to 452 Caucasians participants. Statistical analysis showed a statistical significant difference between Chinese and Caucasian Healthy subjects in the values of SPA1 (p = 0.008), Arth (p = 0.008), and SSI (p < 0.001). Conversely, DA, A1v, DAratio, and 1/R were not significantly different between the two ethnical groups (p > 0.05). Conclusion We found significant differences in the values of the DCRs provided by the Corvis ST between Chinese and Caucasian healthy subjects.
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Affiliation(s)
| | - Robert Herber
- Department of Ophthalmology, University Hospital Carl Gustav Carus, Dresden, Germany
| | - Yan Wang
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Nankai University Affiliated Eye Hospital, Tianjin, China
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Fengju Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Beijing Ophthalmology and Visual Sciences Key Lab, Capital Medical University, Beijing, China
| | - Xingtao Zhou
- EYE & ENT Hospital of Fudan University, Shanghai, China
| | - Ji Bai
- BAI JI Ophthalmology, Chongqing, China
| | - Keming Yu
- Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Shihao Chen
- Eye Hospital, Wenzhou Medical University, Zhejiang, China
| | | | - Frederik Raiskup
- Department of Ophthalmology, University Hospital Carl Gustav Carus, Dresden, Germany
| | - Paolo Vinciguerra
- Department of Biomedical Sciences, Humanitas University, Milan, Italy
- IRCCS Humanitas Research Hospital, Rozzano, Italy
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24
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Repeatability of Corneal Deformation Response Parameters by Dynamic Ultra High-speed Scheimpflug Imaging in Normal and Keratoconus Eyes. Eye Contact Lens 2022; 48:14-19. [PMID: 34924542 DOI: 10.1097/icl.0000000000000845] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2021] [Indexed: 02/06/2023]
Abstract
PURPOSE To assess the repeatability of corneal dynamic response (CDR) parameters in normal and keratoconus (KC) eyes using ultra high-speed Scheimpflug imaging. METHODS Prospective, comparative, observational study, including eyes of 112 patients that underwent high-speed Scheimpflug imaging analysis (Corvis ST, OCULUS). Twenty-one CDR parameters were evaluated to asses repeatability using: coefficient of repeatability (CR), coefficient of variation, intraclass correlation coefficient (ICC) and within-subject SD. Three consecutive measurements by the same operator were performed for each eye. RESULTS There were no significant differences between the three consecutive measurements for all parameters in both normal and KC eyes. 71.42% (15 of the 21 parameters evaluated) and 85.71% (18 of the 21 parameters) were highly repeatable in the normal and KC group, respectively. The tomographic biomechanical index (TBI), corneal biomechanical index (CBI), and stiffness parameter (SPA1) showed an ICC of 0.978, 0.954, and 0.958 in normal and 0.982, 0.892, and 0.978 in KC eyes, respectively. The CR in normal eyes for TBI, CBI, and SPA1 were 0.169, 0.242, and 14.12, respectively, and for KC eyes 0.06, 0.23, and 13.64, respectively. CONCLUSIONS Most of the corneal dynamic response parameters were highly repeatable in normal and KC eyes.
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25
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On the Relationship between Corneal Biomechanics, Macrostructure, and Optical Properties. J Imaging 2021; 7:jimaging7120280. [PMID: 34940747 PMCID: PMC8706034 DOI: 10.3390/jimaging7120280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 11/16/2022] Open
Abstract
Optical properties of the cornea are responsible for correct vision; the ultrastructure allows optical transparency, and the biomechanical properties govern the shape, elasticity, or stiffness of the cornea, affecting ocular integrity and intraocular pressure. Therefore, the optical aberrations, corneal transparency, structure, and biomechanics play a fundamental role in the optical quality of human vision, ocular health, and refractive surgery outcomes. However, the inter-relationships of those properties are not yet reported at a macroscopic scale within the hierarchical structure of the cornea. This work explores the relationships between the biomechanics, structure, and optical properties (corneal aberrations and optical density) at a macro-structural level of the cornea through dual Placido–Scheimpflug imaging and air-puff tonometry systems in a healthy young adult population. Results showed correlation between optical transparency, corneal macrostructure, and biomechanics, whereas corneal aberrations and in particular spherical terms remained independent. A compensation mechanism for the spherical aberration is proposed through corneal shape and biomechanics.
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26
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Karamichos D, Escandon P, Vasini B, Nicholas SE, Van L, Dang DH, Cunningham RL, Riaz KM. Anterior pituitary, sex hormones, and keratoconus: Beyond traditional targets. Prog Retin Eye Res 2021; 88:101016. [PMID: 34740824 PMCID: PMC9058044 DOI: 10.1016/j.preteyeres.2021.101016] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 12/13/2022]
Abstract
"The Diseases of the Horny-coat of The Eye", known today as keratoconus, is a progressive, multifactorial, non-inflammatory ectatic corneal disorder that is characterized by steepening (bulging) and thinning of the cornea, irregular astigmatism, myopia, and scarring that can cause devastating vision loss. The significant socioeconomic impact of the disease is immeasurable, as patients with keratoconus can have difficulties securing certain jobs or even joining the military. Despite the introduction of corneal crosslinking and improvements in scleral contact lens designs, corneal transplants remain the main surgical intervention for treating keratoconus refractory to medical therapy and visual rehabilitation. To-date, the etiology and pathogenesis of keratoconus remains unclear. Research studies have increased exponentially over the years, highlighting the clinical significance and international interest in this disease. Hormonal imbalances have been linked to keratoconus, both clinically and experimentally, with both sexes affected. However, it is unclear how (molecular/cellular signaling) or when (age/disease stage(s)) those hormones affect the keratoconic cornea. Previous studies have categorized the human cornea as an extragonadal tissue, showing modulation of the gonadotropins, specifically luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Studies herein provide new data (both in vitro and in vivo) to further delineate the role of hormones/gonadotropins in the keratoconus pathobiology, and propose the existence of a new axis named the Hypothalamic-Pituitary-Adrenal-Corneal (HPAC) axis.
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Affiliation(s)
- Dimitrios Karamichos
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA.
| | - Paulina Escandon
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Brenda Vasini
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Sarah E Nicholas
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Lyly Van
- University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA; Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Deanna H Dang
- College of Medicine, University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA
| | - Rebecca L Cunningham
- Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Kamran M Riaz
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Bronte-Ciriza D, Birkenfeld JS, de la Hoz A, Curatolo A, Germann JA, Villegas L, Varea A, Martínez-Enríquez E, Marcos S. Estimation of scleral mechanical properties from air-puff optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2021; 12:6341-6359. [PMID: 34745741 PMCID: PMC8548012 DOI: 10.1364/boe.437981] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 08/15/2021] [Accepted: 08/15/2021] [Indexed: 05/11/2023]
Abstract
We introduce a method to estimate the biomechanical properties of the porcine sclera in intact eye globes ex vivo, using optical coherence tomography that is coupled with an air-puff excitation source, and inverse optimization techniques based on finite element modeling. Air-puff induced tissue deformation was determined at seven different locations on the ocular globe, and the maximum apex deformation, the deformation velocity, and the arc-length during deformation were quantified. In the sclera, the experimental maximum deformation amplitude and the corresponding arc length were dependent on the location of air-puff excitation. The normalized temporal deformation profile of the sclera was distinct from that in the cornea, but similar in all tested scleral locations, suggesting that this profile is independent of variations in scleral thickness. Inverse optimization techniques showed that the estimated scleral elastic modulus ranged from 1.84 ± 0.30 MPa (equatorial inferior) to 6.04 ± 2.11 MPa (equatorial temporal). The use of scleral air-puff imaging holds promise for non-invasively investigating the structural changes in the sclera associated with myopia and glaucoma, and for monitoring potential modulation of scleral stiffness in disease or treatment.
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Affiliation(s)
- David Bronte-Ciriza
- Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
- CNR - IPCF, Istituto per i Processi Chimico-Fisici, Messina, Italy
- Co-first authors
| | - Judith S Birkenfeld
- Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
- Co-first authors
| | - Andrés de la Hoz
- Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
| | - Andrea Curatolo
- Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
- International Centre for Translational Eye Research, Warsaw, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - James A Germann
- Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
| | - Lupe Villegas
- Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
| | - Alejandra Varea
- Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
| | - Eduardo Martínez-Enríquez
- Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
| | - Susana Marcos
- Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
- Center for Visual Science, The Institute of Optics, Flaum Eye Institute, University of Rochester, NY 14642, USA
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Chameettachal S, Puranik CJ, Veluthedathu MN, Chalil NB, John R, Pati F. Thickening of Ectatic Cornea through Regeneration Using Decellularized Corneal Matrix Injectable Hydrogel: A Strategic Advancement to Mitigate Corneal Ectasia. ACS APPLIED BIO MATERIALS 2021; 4:7300-7313. [PMID: 35006959 DOI: 10.1021/acsabm.1c00821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ectatic corneal diseases are a group of eye disorders characterized by progressive thinning and outward bulging of the cornea, resulting in vision impairment. A few attempts have been made to use cornea-derived extracellular matrix hydrogels for corneal tissue engineering; however, no studies have investigated its application in corneal ectasia. In this study, we have first developed an animal surgical model that mimics a few specific phenotypes of ectatic cornea. Later, we investigated the potential of decellularized cornea matrix hydrogels (dCMH) from both human and bovine sources in increasing the thickness of the cornea in the developed surgical model. Our data advocate that surgical stromal depletion can be followed to establish ectatic models and can also provide information on the biocompatibility of materials, its integration with native stroma, degradation over time, and tissue remodeling. We observed that dCMH from both sources could integrate with ectatic thin corneal stroma and helps in regaining the thickness by regenerating a reasonably functional and transparent stroma; however, no significant difference was spotted between the dCMH made from human and bovine corneal tissue sources. Hence, this study is a promising step toward developing a non-invasive technique for the treatment of corneal ectasia by using dCMH.
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Affiliation(s)
- Shibu Chameettachal
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy Hyderabad, Telangana 502284, India
| | - Charuta J Puranik
- Oculus Regenerus Eye Care and Research Center, Nanalnagar, Hyderabad, Telangana 500008, India
| | - Mohamed Nijas Veluthedathu
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy Hyderabad, Telangana 502284, India
| | - Najathulla Bhagavathi Chalil
- Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy , Hyderabad, Telangana 502284, India
| | - Renu John
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy Hyderabad, Telangana 502284, India
| | - Falguni Pati
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy Hyderabad, Telangana 502284, India
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29
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Corneal Tomography Multivariate Index (CTMVI) effectively distinguishes healthy corneas from those susceptible to ectasia. Biomed Signal Process Control 2021. [DOI: 10.1016/j.bspc.2021.102995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Iqbal M, Mounir A, Abd-Elaziz K, Said OM. Long-Term Visual, Refractive and Topographic Outcomes of KeraRings Combined with Accelerated Transepithelial Crosslinking for Management of Different Grades of Progressive Keratoconus: A Retrospective Cohort Study. Open Ophthalmol J 2021. [DOI: 10.2174/1874364102115010054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Purpose:
To evaluate long-term visual, refractive, and topographic outcomes of KeraRings intrastromal implantation combined with accelerated transepithelial cross-linking for management of different stages of progressive keratoconus.
Materials and Methods:
This retrospective cohort study included 70 eyes of 70 patients with Amsler-Krumeich grades 1 to 4 keratoconus. They were divided into two groups: group-A included 37 eyes with grades 1-2 keratoconus, and group-B included 33 eyes with grades 3-4 keratoconus. Both groups underwent combined Keraring implantation with TCXL treatment. The main outcome measures included the preoperative and postoperative visual acuity, refraction, keratometry readings, and pachymetry.
Results:
At postoperative month 60, group-B exhibited significantly higher values of all mean uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), sphere/cylinder/spherical equivalent/defocus equivalent (DEQ), and K1/K2/Kaverages/Kmax parameters compared to that of group A. However, group-A exhibited better stability of postoperative improvements. Keratoconus progression (KCP) was greater in group-B (45.5%) than group-A (10.8%). Two eyes revealed segments' migration while one eye showed tunnel vascularization and opacification with segments' migration.
Conclusion:
The diagnostic criteria of preoperative-KCP are not adequate for the diagnosis of postoperative-KCP following ICRS implantation. UDVA and K average posterior seemed to be more sensitive parameters than K max in documenting early postoperative-KCP. We suggest that deterioration of UDVA≥0.10 log MAR and/or K average posterior ≥0.25 D are highly suspicious of post-ring implantation keratoconus progression (PR-KCP). The occurrence of two of the following parameters: Kmax≥0.50 D, Kaverageanterior≥0.50 D, K average posterior ≥0.25 D, or pachymetry≥1.5% thinning, is diagnostic of PR-KCP. The occurrence of two or more of the following parameters: Kmax≥0.50 D, Kaverageanterior≥0.50 D, Kaverageposterior ≥0.25 D, pachymetry≥ 1.5% thinning or UDVA≥0.10 logMAR, is diagnostic of PR-KCP. We also suggest that Kmax≥0.75 D alone is diagnostic of PR-KCP.
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31
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Baptista PM, Ambrosio R, Oliveira L, Meneres P, Beirao JM. Corneal Biomechanical Assessment with Ultra-High-Speed Scheimpflug Imaging During Non-Contact Tonometry: A Prospective Review. Clin Ophthalmol 2021; 15:1409-1423. [PMID: 33854295 PMCID: PMC8039844 DOI: 10.2147/opth.s301179] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/05/2021] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND In recent years, increasing interest has arisen in the application of data from corneal biomechanics in many areas of ophthalmology, particularly to assist in the detection of early corneal ectasia or ectasia susceptibility, to predict corneal response to surgical or therapeutic interventions and in glaucoma management. Technology has evolved and, recently, the Scheimpflug principle was associated with a non-contact air-puff tonometer, allowing a thorough analysis of corneal biomechanics and a biomechanically corrected intraocular pressure assessment, opening up new perspectives both in ophthalmology and in other medical areas. Data from corneal biomechanics assessment are being integrated in artificial intelligence models in order to increase its value in clinical practice. OBJECTIVE To review the state of the art in the field of corneal biomechanics assessment with special emphasis to the technology based on ultra-high-speed Scheimpflug imaging during non-contact tonometry. SUMMARY A meticulous literature review was performed until the present day. We used 136 published manuscripts as our references. Both information from healthy individuals and descriptions of possible associations with systemic diseases are described. Additionally, it exposed information regarding several fields of ocular pathology, from cornea and ocular surface through areas of refractive surgery and glaucoma until vascular and structural diseases of the chorioretinal unit.
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Affiliation(s)
- Pedro Manuel Baptista
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal
| | - Renato Ambrosio
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, RJ, Brazil
- Department of Cornea and Refractive Surgery, Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Department of Opthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
- Federal University of São Paulo (UNIFESP), São Paulo, Brazil
- Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro & Maceió, Brazil
| | - Luis Oliveira
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Pedro Meneres
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal
| | - Joao Melo Beirao
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal
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Moscovici BK, Rodrigues PF, Rodrigues RAM, Rios LC, Simoncelli R, Freitas MMS, Torquetti L. Evaluation of keratoconus progression and visual improvement after intrastromal corneal ring segments implantation: A retrospective study. Eur J Ophthalmol 2021; 31:3483-3489. [PMID: 33719637 DOI: 10.1177/11206721211000646] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To investigate the role of ICRS in halting keratoconus progression in a large sample of patients. METHODS A retrospective, non-comparative, interventional study based on the review of medical records of patients diagnosed with keratoconus who underwent Ferrara corneal ring segment implantation. A retrospective chart analysis study of 123 operated eyes with follow-up ranging from 3 to 16 years (mean 5.3 ± 3.6 years) was performed. This study was carried out at Ocular Surgery Unit, São Paulo, Brazil. All topographic data were obtained from Pentacam (Oculus, Arlington, USA). The same surgeon performed all surgeries, and the Ferrara ICRS nomogram was used for ICRS selection in all cases. RESULTS Corrected distance visual acuity, keratometry, and topographic astigmatism improved in most cases, with statistical significance. In 42 eyes (53.8%), there was an increase in K1 or K2, and in 36 (46.2%), there was a reduction or maintenance in K1. Considering a difference higher than 1 D, between 3-month post-surgery and final visit (group 3), 32 eyes (41%) showed an increase, and 46 eyes (59%) ended equal or below this value. CONCLUSION The implantation of ICRS showed improvement in visual and keratometric indexes. The majority of patients did not increase more than one diopter in keratometric values after ICRS implantation. ICRS may be effective for slowing disease progression, especially in older patients.
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Abstract
PURPOSE Diabetes mellitus (DM) induces changes in corneal biomechanical properties. The influence of disease-specific factors was evaluated, and a novel DM index was created. METHODS Eighty-one patients with DM and 75 healthy subjects were matched according to age, intraocular pressure, and central corneal thickness. Information on the disease was collected, and measurements with the Ocular Response Analyzer and the Corvis ST were taken. Results were compared between the groups, and the influence of disease-specific factors was evaluated. From dynamic corneal response parameters, a DM index was calculated. RESULTS In DM, corneal hysteresis was higher than in healthy subjects (10.5 ± 1.9 vs. 9.7 ± 1.9 mm Hg, P = 0.008). In addition, dynamic corneal response parameters showed significant differences. Among others, highest concavity (HC) (17.212 ± 0.444 vs. 16.632 ± 0.794 ms, P < 0.001) and A2 time (21.85 ± 0.459 vs. 21.674 ± 0.447 ms, P = 0.017) as well as A1 (0.108 ± 0.008 vs. 0.104 ± 0.011 mm, P = 0.019) and A2 deflection amplitudes (0.127 ± 0.014 vs. 0.119 ± 0.014 mm, P < 0.001) were increased in DM. In DM type 1, HC deformation amplitude (1.14 ± 0.19 vs. 1.095 ± 0.114 mm, P = 0.035) was higher than in type 2. The time of deflection amplitude max correlated with the severity of retinopathy (R = 0.254, P= 0.023). In case of diabetic maculopathy, A1 velocity (0.155 ± 0.018 vs. 0.144 ± 0.019 ms, P = 0.043) and A2 time (22.052 ± 0.395 vs. 21.79 ± 0.46 ms, P = 0.04) were increased. Deformation amplitude max (R = 0.297, P = 0.024), HC time (R = 0.26, P = 0.049), HC deformation amplitude (R = 0.297, P = 0.024), and A2 deformation amplitude (R = 0.276, P = 0.036) were associated to disease duration. The DM index revealed a sensitivity of 0.773 and a specificity of 0.808 (area under the curve of receiver operating characteristic = 0.833). CONCLUSIONS In DM, changes in corneal biomechanics were correlated with disease-specific factors. The DM index achieved reliable sensitivity and specificity values.
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Li Y, Xu Z, Liu Q, Wang Y, Lin K, Xia J, Chen S, Hu L. Relationship between corneal biomechanical parameters and corneal sublayer thickness measured by Corvis ST and UHR-OCT in keratoconus and normal eyes. EYE AND VISION 2021; 8:2. [PMID: 33419485 PMCID: PMC7796648 DOI: 10.1186/s40662-020-00225-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/14/2020] [Indexed: 12/27/2022]
Abstract
BACKGROUND To explore the relationship between corneal biomechanical parameters and corneal sublayer thickness using corneal visualization Scheimpflug technology (Corvis ST) and ultrahigh-resolution optical coherence tomography (UHR-OCT) in clinical and suspected keratoconus and normal eyes. METHODS Cross-sectional prospective study. A total of 94 eyes of 70 participants were recruited. Twenty five eyes of 19 keratoconus patients, 52 eyes of 34 patients showing high risk of developing keratoconus according to the Belin/Ambrosio Enhanced Ectasia Display, and each eye of 17 normal subjects were enrolled. All participants underwent Corvis ST, Pentacam, and UHR-OCT examinations at the same time. Stiffness parameter A1 (SP-A1), deformation amplitude ratio (DA ratio), and other biomechanical parameters were recorded using Corvis ST. The vertical and horizontal thickness profiles of central 3 mm corneal epithelium, Bowman's layer, and stroma as measured by the perpendicular distance between the neighboring interfaces were generated using UHR-OCT. The flat keratometry and steep keratometry were obtained using Pentacam. Analysis of correlation was applied to explore the association between variables. RESULTS Most of the biomechanical parameters and corneal sublayer thickness profiles showed statistical differences among three groups. A statistically significant linear relationship was noted between SP-A1 and DA ratio in all three groups. SP-A1 was found to be positively correlated with epithelial and Bowman's layer thickness in the keratoconus (KC) group, and with stromal thickness in all three groups. In the normal and suspected keratoconus (SKC) groups, only stromal thickness was included in the stepwise linear regression to predict SP-A1, whereas in the KC group, steep keratometry and Bowman's layer thickness were included. CONCLUSIONS Significant and different correlations were noted between corneal stiffness and corneal sublayer thickness in different groups, indicating that corneal sublayers may play different roles in maintaining corneal biomechanical stability between keratoconus and normal eyes.
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Affiliation(s)
- Yong Li
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang, China
| | - Zhiqiang Xu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang, China
| | - Qiaoli Liu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang, China
| | - Yuzhou Wang
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang, China
| | - Kan Lin
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang, China
| | - Jiahui Xia
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China.,National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang, China
| | - Shihao Chen
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China. .,National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang, China.
| | - Liang Hu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China. .,National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang, China.
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Preoperative, intraoperative, and postoperative assessment of corneal biomechanics in refractive surgery. Curr Opin Ophthalmol 2020; 31:234-240. [PMID: 32452876 DOI: 10.1097/icu.0000000000000663] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
PURPOSE OF REVIEW To review current and emerging methods and utilities of preoperative, intraoperative, and postoperative measurements of corneal biomechanics and their effects on refractive surgery decision-making. RECENT FINDINGS Several recent clinical and preclinical studies have demonstrated the utility of corneal biomechanical analysis in refractive surgery. These studies focus on both screening surgical candidates for keratoconic disease as well as intraoperative and postoperative monitoring. The measurement of spatially resolved biomechanics is beginning to be studied in humans. SUMMARY Clinically available screening methods combining corneal biomechanics with topographic and tomographic data provide increased utility when screening for keratoconic disorder. Spatially resolved measurement of corneal biomechanics holds great potential for preoperative, intraoperative, and postoperative evaluation of refractive surgery candidates as well as for more individualized procedures in the future.
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Yang K, Xu L, Fan Q, Gu Y, Song P, Zhang B, Zhao D, Pang C, Ren S. Evaluation of new Corvis ST parameters in normal, Post-LASIK, Post-LASIK keratectasia and keratoconus eyes. Sci Rep 2020; 10:5676. [PMID: 32231236 PMCID: PMC7105482 DOI: 10.1038/s41598-020-62825-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 03/17/2020] [Indexed: 12/17/2022] Open
Abstract
The aim of this study was to evaluate the distribution of new Corneal Visualisation Scheimpflug Technology (Corvis ST) parameters in normal, Post-laser in situ keratomileusis (LASIK), Post-LASIK keratectasia (KE) and keratoconus (KC) eyes, and explore the diagnostic ability of these parameters in distinguishing KE from LASIK eyes. Twenty-three normal eyes, 23 LASIK eyes, 23 KE eyes and 23 KC eyes were recruited in this study. The following new Corvis ST parameters were measured: Max Inverse Radius, deformation amplitude (DA) Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Ambrosio’s relational thickness horizontal (ARTh), Integrated Radius, stiffness parameter at first applanation (SP-A1) and Corvis biomechanical index (CBI). The general linear model, linear regression model, relation analysis and receiver operating characteristic (ROC) curve were performed. The Max Inverse Radius, DA Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Integrated Radius and CBI in LASIK eyes, KE eyes and KC eyes were higher than in normal eyes, while the ARTh and SP-A1 parameters were lower than in normal eyes. The KE eyes had higher Max Inverse Radius, DA Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Integrated Radius, and lower SP-A1 value than LASIK eyes (all P < 0.05). The central corneal thickness was related to the Pachy Slope (r = −0.485), ARTh (r = −0.766), SP-A1 (r = 0.618) in KE eyes (all P < 0.05). The area under the ROC curve of Integrated Radius, Max Inverse Radius, DA Ratio Max [2 mm] and SP-A1 were above 0.800 in identifying KE from LASIK eyes. Thus, the new Corvis ST parameters were different between LASIK and KE eyes, suggesting that they might be helpful in distinguishing KE eyes from LASIK eyes. However, a further multi-center and large sample study is necessary to confirm these findings.
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Affiliation(s)
- Kaili Yang
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Liyan Xu
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Qi Fan
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Yuwei Gu
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Peng Song
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Bo Zhang
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Dongqing Zhao
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Chenjiu Pang
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China.
| | - Shengwei Ren
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China.
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Salomão MQ, Hofling-Lima AL, Gomes Esporcatte LP, Lopes B, Vinciguerra R, Vinciguerra P, Bühren J, Sena N, Luz Hilgert GS, Ambrósio R. The Role of Corneal Biomechanics for the Evaluation of Ectasia Patients. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17062113. [PMID: 32209975 PMCID: PMC7143615 DOI: 10.3390/ijerph17062113] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/12/2020] [Accepted: 03/14/2020] [Indexed: 12/16/2022]
Abstract
Purpose: To review the role of corneal biomechanics for the clinical evaluation of patients with ectatic corneal diseases. Methods: A total of 1295 eyes were included for analysis in this study. The normal healthy group (group N) included one eye randomly selected from 736 patients with healthy corneas, the keratoconus group (group KC) included one eye randomly selected from 321 patients with keratoconus. The 113 nonoperated ectatic eyes from 125 patients with very asymmetric ectasia (group VAE-E), whose fellow eyes presented relatively normal topography (group VAE-NT), were also included. The parameters from corneal tomography and biomechanics were obtained using the Pentacam HR and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). The accuracies of the tested variables for distinguishing all cases (KC, VAE-E, and VAE-NT), for detecting clinical ectasia (KC + VAE-E) and for identifying abnormalities among the VAE-NT, were investigated. A comparison was performed considering the areas under the receiver operating characteristic curve (AUC; DeLong’s method). Results: Considering all cases (KC, VAE-E, and VAE-NT), the AUC of the tomographic-biomechanical parameter (TBI) was 0.992, which was statistically higher than all individual parameters (DeLong’s; p < 0.05): PRFI- Pentacam Random Forest Index (0.982), BAD-D- Belin -Ambrosio D value (0.959), CBI -corneal biomechanical index (0.91), and IS Abs- Inferior-superior value (0.91). The AUC of the TBI for detecting clinical ectasia (KC + VAE-E) was 0.999, and this was again statistically higher than all parameters (DeLong’s; p < 0.05): PRFI (0.996), BAD-D (0.995), CBI (0.949), and IS Abs (0.977). Considering the VAE-NT group, the AUC of the TBI was 0.966, which was also statistically higher than all parameters (DeLong’s; p < 0.05): PRFI (0.934), BAD- D (0.834), CBI (0.774), and IS Abs (0.677). Conclusions: Corneal biomechanical data enhances the evaluation of patients with corneal ectasia and meaningfully adds to the multimodal diagnostic armamentarium. The integration of biomechanical data and corneal tomography with artificial intelligence data augments the sensitivity and specificity for screening and enhancing early diagnosis. Besides, corneal biomechanics may be relevant for determining the prognosis and staging the disease.
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Affiliation(s)
- Marcella Q. Salomão
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520050, Brazil; (M.Q.S.); (L.P.G.E.); (B.L.)
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520050, Brazil
- Brazilian Study Group of Artificial Intelligence and Corneal Analysis—BrAIN, Rio de Janeiro 20520050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023062, Brazil;
- Instituto Benjamin Constant, Rio de Janeiro 22290255, Brazil
| | - Ana Luisa Hofling-Lima
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023062, Brazil;
| | - Louise Pellegrino Gomes Esporcatte
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520050, Brazil; (M.Q.S.); (L.P.G.E.); (B.L.)
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520050, Brazil
| | - Bernardo Lopes
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520050, Brazil; (M.Q.S.); (L.P.G.E.); (B.L.)
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023062, Brazil;
- School of Engineering, University of Liverpool, L69 3GH Liverpool, UK;
| | - Riccardo Vinciguerra
- School of Engineering, University of Liverpool, L69 3GH Liverpool, UK;
- Humanitas San Pio X Hospital, 20159 Milan, Italy
| | - Paolo Vinciguerra
- The Eye Center, Humanitas Clinical and Research Center, 20089 Rozzano, Italy;
- Vincieye Clinic, 20141 Milan, Italy
| | - Jens Bühren
- Praxis für Augenheikunde Prof. Bühren, D-60431 Frankfurt, Germany;
| | - Nelson Sena
- Department of Ophthalmology, Federal University the state of Rio de Janeiro (UNIRIO), Rio de Janeiro 22290-240, Brazil;
| | | | - Renato Ambrósio
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro 20520050, Brazil; (M.Q.S.); (L.P.G.E.); (B.L.)
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520050, Brazil
- Brazilian Study Group of Artificial Intelligence and Corneal Analysis—BrAIN, Rio de Janeiro 20520050, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023062, Brazil;
- Department of Ophthalmology, Federal University the state of Rio de Janeiro (UNIRIO), Rio de Janeiro 22290-240, Brazil;
- Correspondence:
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Comparison of a New Swept-Source Anterior Segment Optical Coherence Tomography and a Scheimpflug Camera for Measurement of Corneal Curvature. Cornea 2020; 39:818-822. [DOI: 10.1097/ico.0000000000002280] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Esporcatte LPG, Salomão MQ, Lopes BT, Vinciguerra P, Vinciguerra R, Roberts C, Elsheikh A, Dawson DG, Ambrósio R. Biomechanical diagnostics of the cornea. EYE AND VISION 2020; 7:9. [PMID: 32042837 PMCID: PMC7001259 DOI: 10.1186/s40662-020-0174-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 01/08/2020] [Indexed: 02/06/2023]
Abstract
Corneal biomechanics has been a hot topic for research in contemporary ophthalmology due to its prospective applications in diagnosis, management, and treatment of several clinical conditions, including glaucoma, elective keratorefractive surgery, and different corneal diseases. The clinical biomechanical investigation has become of great importance in the setting of refractive surgery to identify patients at higher risk of developing iatrogenic ectasia after laser vision correction. This review discusses the latest developments in the detection of corneal ectatic diseases. These developments should be considered in conjunction with multimodal corneal and refractive imaging, including Placido-disk based corneal topography, Scheimpflug corneal tomography, anterior segment tomography, spectral-domain optical coherence tomography (SD-OCT), very-high-frequency ultrasound (VHF-US), ocular biometry, and ocular wavefront measurements. The ocular response analyzer (ORA) and the Corvis ST are non-contact tonometry systems that provide a clinical corneal biomechanical assessment. More recently, Brillouin optical microscopy has been demonstrated to provide in vivo biomechanical measurements. The integration of tomographic and biomechanical data into artificial intelligence techniques has demonstrated the ability to increase the accuracy to detect ectatic disease and characterize the inherent susceptibility for biomechanical failure and ectasia progression, which is a severe complication after laser vision correction.
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Affiliation(s)
- Louise Pellegrino Gomes Esporcatte
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.,Instituto de Olhos Renato Ambrósio, Rua Conde de Bonfim 211 / 712, Rio de Janeiro, RJ 20520-050 Brazil.,3Department of Ophthalmology, Hospital São Vicente de Paulo, Rio de Janeiro, Brazil
| | - Marcella Q Salomão
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.,Instituto de Olhos Renato Ambrósio, Rua Conde de Bonfim 211 / 712, Rio de Janeiro, RJ 20520-050 Brazil.,Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro & Maceió, Brazil.,5Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.,Instituto Benjamin Constant, Rio de Janeiro, Brazil
| | - Bernardo T Lopes
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.,7School of Engineering, University of Liverpool, Liverpool, L69 3GH UK
| | - Paolo Vinciguerra
- 8Department of Biomedical Science, Humanitas University, Rozzano, Italy.,9Eye Center, Humanitas Clinical and Research Center, Rozzano, Italy
| | - Riccardo Vinciguerra
- 7School of Engineering, University of Liverpool, Liverpool, L69 3GH UK.,Department of Ophthalmology, Humanitas San Pio X Hospital, Milan, Italy
| | - Cynthia Roberts
- 11Department of Ophthalmology and Visual Science, Department of Biomedical Engineering, The Ohio State University, Columbus, OH USA
| | - Ahmed Elsheikh
- 7School of Engineering, University of Liverpool, Liverpool, L69 3GH UK.,12School of Biological Science and Biomedical Engineering, Beihang University, Beijing, China.,13NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - Daniel G Dawson
- 14The University of Florida Department of Ophthalmology, Gainesville, FL USA
| | - Renato Ambrósio
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.,Instituto de Olhos Renato Ambrósio, Rua Conde de Bonfim 211 / 712, Rio de Janeiro, RJ 20520-050 Brazil.,Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro & Maceió, Brazil.,5Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.,15Department of Ophthalmology, Federal University the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
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Oberflächenverfahren in der refraktiven Chirurgie. SPEKTRUM DER AUGENHEILKUNDE 2019. [DOI: 10.1007/s00717-019-00439-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Ramm L, Herber R, Spoerl E, Pillunat LE, Terai N. Intraocular pressure measurements in diabetes mellitus. Eur J Ophthalmol 2019; 30:1432-1439. [PMID: 31779470 DOI: 10.1177/1120672119890517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE To investigate the impact of diabetes mellitus-induced changes on intraocular pressure measurements using Goldmann applanation tonometry, Ocular Response Analyzer, and Corvis ST. METHODS Measurements were done using Goldmann applanation tonometry, Ocular Response Analyzer, and Corvis ST in 69 diabetic patients. Biomechanical-corrected intraocular pressure values by Ocular Response Analyzer (IOPcc) and Corvis ST (bIOP) were used. In addition, biometry and tomography were performed and information on diabetes mellitus specific factors was collected. Results were compared to an age-matched group of 68 healthy subjects. RESULTS In diabetes mellitus, Goldmann applanation tonometry intraocular pressure (P = 0.193) and central corneal thickness (P = 0.184) were slightly increased. Also, IOPcc (P = 0.075) and bIOP (P = 0.542) showed no significant group difference. In both groups, IOPcc was higher than Goldmann applanation tonometry intraocular pressure (P = 0.002, P < 0.001), while bIOP was nearly equal to Goldmann applanation tonometry intraocular pressure (P = 0.795, P = 0.323). Central corneal thickness showed a tendency to higher values in poorly controlled than in controlled diabetes mellitus (P = 0.059). Goldmann applanation tonometry intraocular pressure correlated to central corneal thickness, while IOPcc and bIOP were independent from central corneal thickness in both groups. All intraocular pressure values showed significant associations to corneal biomechanical parameters. Only in diabetes mellitus, bIOP was correlated to Pachy slope (P = 0.023). CONCLUSION In diabetes mellitus, Goldmann applanation tonometry intraocular pressure was slightly, but not significantly, increased, which might be caused by a higher central corneal thickness and changes in corneal biomechanical properties. However, intraocular pressure values measured by Ocular Response Analyzer and Corvis ST were not significantly different between diabetes mellitus patients and healthy subjects. The bIOP showed a higher agreement with Goldmann applanation tonometry than IOPcc and was independent from central corneal thickness.
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Affiliation(s)
- Lisa Ramm
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Germany
| | - Robert Herber
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Germany
| | - Eberhard Spoerl
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Germany
| | - Lutz E Pillunat
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Germany
| | - Naim Terai
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Germany
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Francis M, Matalia H, Nuijts RMMA, Haex B, Shetty R, Sinha Roy A. Corneal Viscous Properties Cannot Be Determined From Air-Puff Applanation. J Refract Surg 2019; 35:730-736. [PMID: 31710375 DOI: 10.3928/1081597x-20191010-03] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 10/10/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess whether corneal viscous properties are measureable with air-puff applanation in patients. METHODS The study had 312 normal eyes, 107 fellow eyes of patients with keratoconus, and 289 keratoconic eyes. The Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) deformation data for all eyes were analyzed using two models. First, a standard linear solid model (SLM) assumed the cornea was an elastic material only. Second, a two-compartment Kelvin-Voigt model (KVM) assumed the cornea was a visco-elastic material. Corneal stiffness and viscosity were calculated. Further, the deflection amplitude was phase shifted virtually relative to the air-puff applanation force to assess whether the KVM was capable of detecting corneal viscous properties from air-puff applanation. This was similar in concept to measured viscoelastic deformations in other soft tissues. The hysteresis area was also calculated with deformation (cornea and whole globe) and deflection (cornea only) amplitude. The greater the magnitude of the hysteresis area, the greater was the magnitude of corneal viscosity (µc). RESULTS Both the SLM and KVM reported similar magnitudes of corneal stiffnesses (correlation coefficient > 0.99). However, for a given model, corneal stiffness was significantly different between normal, fellow, and keratoconic eyes (P = .001). From the KVM, the corneal viscosity was different between groups (P = .001) but was small in magnitude (order of 10-9). The deflection hysteresis area was also small in magnitude (order of 10-6). In contrast, the KVM detected significant corneal viscosity only when the deflection amplitude was virtually phase shifted with respect to the air-puff applanation force. CONCLUSIONS No significant corneal viscous response was detected in patients who had air-puff applanation. [J Refract Surg. 2019;35(11):730-736.].
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Eliasy A, Chen KJ, Vinciguerra R, Lopes BT, Abass A, Vinciguerra P, Ambrósio R, Roberts CJ, Elsheikh A. Determination of Corneal Biomechanical Behavior in-vivo for Healthy Eyes Using CorVis ST Tonometry: Stress-Strain Index. Front Bioeng Biotechnol 2019; 7:105. [PMID: 31157217 PMCID: PMC6532432 DOI: 10.3389/fbioe.2019.00105] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 04/24/2019] [Indexed: 11/25/2022] Open
Abstract
Purpose: This study aims to introduce and clinically validate a new algorithm that can determine the biomechanical properties of the human cornea in vivo. Methods: A parametric study was conducted involving representative finite element models of human ocular globes with wide ranges of geometries and material biomechanical behavior. The models were subjected to different levels of intraocular pressure (IOP) and the action of external air puff produced by a non-contact tonometer. Predictions of dynamic corneal response under air pressure were analyzed to develop an algorithm that can predict the cornea's material behavior. The algorithm was assessed using clinical data obtained from 480 healthy participants where its predictions of material behavior were tested against variations in central corneal thickness (CCT), IOP and age, and compared against those obtained in earlier studies on ex-vivo human ocular tissue. Results: The algorithm produced a material stiffness parameter (Stress-Strain Index or SSI) that showed no significant correlation with both CCT (p > 0.05) and IOP (p > 0.05), but was significantly correlated with age (p < 0.01). The stiffness estimates and their variation with age were also significantly correlated (p < 0.01) with stiffness estimates obtained earlier in studies on ex-vivo human tissue. Conclusions: The study introduced and validated a new method for estimating the in vivo biomechanical behavior of healthy corneal tissue. The method can aid optimization of procedures that interfere mechanically with the cornea such as refractive surgeries and introduction of corneal implants.
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Affiliation(s)
- Ashkan Eliasy
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Kai-Jung Chen
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Riccardo Vinciguerra
- School of Engineering, University of Liverpool, Liverpool, United Kingdom.,St Paul's Eye Unit, Royal Liverpool and Broadgreen University Hospital, Liverpool, United Kingdom
| | - Bernardo T Lopes
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Paolo Vinciguerra
- Department of Biomedical Science, Humanitas University, Rozzano, Italy.,Eye Center, Humanitas Clinical and Research Center, Rozzano, Italy
| | - Renato Ambrósio
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.,Department of Ophthalmology, Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Cynthia J Roberts
- Department of Ophthalmology and Visual Science, Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, United Kingdom.,NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom.,School of Biological Science and Biomedical Engineering, Beihang University, Beijing, China
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Leão E, Ing Ren T, Lyra JM, Machado A, Koprowski R, Lopes B, Vinciguerra R, Vinciguerra P, Roberts CJ, Elsheikh A, Krysik K, Ambrósio R. Corneal deformation amplitude analysis for keratoconus detection through compensation for intraocular pressure and integration with horizontal thickness profile. Comput Biol Med 2019; 109:263-271. [PMID: 31096090 DOI: 10.1016/j.compbiomed.2019.04.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/25/2019] [Accepted: 04/20/2019] [Indexed: 01/03/2023]
Abstract
BACKGROUND The Corvis ST provides measurements of intraocular pressure (IOP) and a biomechanically-corrected IOP (bIOP). IOP influences corneal deflection amplitude (DA), which may affect the diagnosis of keratoconus. Compensating for IOP in DA values may improve the detection of keratoconus. METHODS 195 healthy eyes and 136 eyes with keratoconus were included for developing different approaches to distinguish normal and keratoconic corneas using attribute selection and discriminant function. The IOP compensation is proposed by dividing the DA by the IOP values. The first approaches include DA compensated for either IOP or bIOP and other parameters from the deformation corneal response (DCR). Another approach integrated the horizontal corneal thickness profile (HCTP). The best classifiers developed were applied in a validation database of 156 healthy eyes and 87 eyes with keratoconus. Results were compared with the current Corvis Biomechanical Index (CBI). RESULTS The best biomechanical approach used the DA values compensated by IOP (Approach 2) using a linear discriminant function and reached AUC 0.954, with a sensitivity of 88.2% and a specificity of 97.4%. When thickness horizontal profile data was integrated (Approach 4), the best function was the diagquadratic, resulting in an AUC of 0.960, with a sensitivity of 89.7% and a specificity of 96.4%. There was no significant difference in the results between approaches 2 and 4 with the CBI in the training and validation databases. CONCLUSIONS By compensating for the IOP, and with the horizontal thickness profile included or excluded, it was possible to generate a classifier based only on biomechanical information with a similar result to the CBI.
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Affiliation(s)
- Edileuza Leão
- Centro de Informática (CIn) - Universidade Federal de Pernambuco (UFPE) - v. Jornalista Aníbal Fernandes, Cidade Universitária, 50740-560, Recife, PE, Brazil; Universidade Estadual de Ciências da Saúde de Alagoas (UNCISAL), Brazil; Brazilian Study Group of Artificial Intelligence and Corneal Analysis (BrAIn), Brazil.
| | - Tsang Ing Ren
- Centro de Informática (CIn) - Universidade Federal de Pernambuco (UFPE) - v. Jornalista Aníbal Fernandes, Cidade Universitária, 50740-560, Recife, PE, Brazil; Brazilian Study Group of Artificial Intelligence and Corneal Analysis (BrAIn), Brazil
| | - João M Lyra
- Universidade Estadual de Ciências da Saúde de Alagoas (UNCISAL), Brazil; Brazilian Study Group of Artificial Intelligence and Corneal Analysis (BrAIn), Brazil
| | - Aydano Machado
- Instituto de Computação (IC) - Universidade Federal de Alagoas (UFAL), Brazil; Brazilian Study Group of Artificial Intelligence and Corneal Analysis (BrAIn), Brazil
| | - Robert Koprowski
- Department of Biomedical Computer Systems, University of Silesia, Faculty of Computer Science and Materials Science, Institute of Computer Science, Brazil
| | - Bernado Lopes
- Department of Ophthalmology of Federal University of São Paulo, São Paulo, Brazil; School of Engineering, University of Liverpool, Liverpool, UK
| | | | | | - Cynthia J Roberts
- Department of Ophthalmology Visual Science and Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, UK; National Institute for Health Research (NIHR) Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK; School of Biological Science and Biomedical Engineering, Beihang University, Beijing, China
| | - Katarzyna Krysik
- Department of Ophthalmology with Paediatric Unit, St. Barbara Hospital, Trauma Center, Sosnowiec, Poland
| | - Renato Ambrósio
- (d)Federal University of the State of Rio de Janeiro, Brazil; Department of Ophthalmology of Federal University of São Paulo, São Paulo, Brazil; Brazilian Study Group of Artificial Intelligence and Corneal Analysis (BrAIn), Brazil
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Jędzierowska M, Koprowski R. Novel dynamic corneal response parameters in a practice use: a critical review. Biomed Eng Online 2019; 18:17. [PMID: 30760270 PMCID: PMC6375180 DOI: 10.1186/s12938-019-0636-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/08/2019] [Indexed: 12/27/2022] Open
Abstract
Background Non-contact tonometers based on the method using air puff and Scheimpflug’s fast camera are one of the latest devices allowing the measurement of intraocular pressure and additional biomechanical parameters of the cornea. Biomechanical features significantly affect changes in intraocular pressure values, as well as their changes, may indicate the possibility of corneal ectasia. This work presents the latest and already known biomechanical parameters available in the new offered software. The authors focused on their practical application and the diagnostic credibility indicated in the literature. Discussion An overview of available literature indicates the importance of new dynamic corneal parameters. The latest parameters developed on the basis of biomechanics analysis of corneal deformation process, available in non-contact tonometers using Scheimpflug’s fast camera, are used in the evaluation of laser refractive surgery procedures, e.g. LASIK procedure. In addition, the assessment of changes in biomechanically corrected intraocular pressure confirms its independence from changes in the corneal biomechanics which may allow an intraocular pressure real assessment. The newly developed Corvis Biomechanical Index combined with the corneal tomography and topography assessment is an important aid in the classification of patients with keratoconus. Conclusion New parameters characterising corneal deformation, including Corvis Biomechanical Index and biomechanical compensated intraocular pressure, significantly extend the diagnostic capabilities of this device and may be helpful in assessing corneal diseases of the eye. Nevertheless, further research is needed to confirm their diagnostic pertinence.
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Affiliation(s)
- Magdalena Jędzierowska
- Department of Biomedical Computer Systems, Faculty of Computer Science and Materials Science, Institute of Computer Science, University of Silesia, ul. Będzińska 39, 41-200, Sosnowiec, Poland.
| | - Robert Koprowski
- Department of Biomedical Computer Systems, Faculty of Computer Science and Materials Science, Institute of Computer Science, University of Silesia, ul. Będzińska 39, 41-200, Sosnowiec, Poland
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Measurement of Corneal Biomechanical Properties in Diabetes Mellitus Using the Ocular Response Analyzer and the Corvis ST. Cornea 2019; 38:595-599. [DOI: 10.1097/ico.0000000000001879] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Abstract
Corneal ectasia has emerged as a serious complication of laser vision correction (LVC) procedures since the first report by Seiler in 1998. Thereby, its prevention has become a major concern for refractive surgeons. Ectasia occurs due to biomechanical decompensation of the stroma, which may be related to a severe impact on corneal structure (i.e., attempted treatment for high myopia) or the altered biomechanical properties preoperatively. The current understanding is that a combination from those factors determines stability or ectasia progression after LVC. Abnormal corneal topography has been the most important surrogate for lower biomechanical properties, but novel imaging technologies such as tomography and biomechanical assessment have proven to enhance the ability for detecting mild ectatic disease, such as in the eyes with normal topography from patients with clinical ectasia in the fellow eye. Bohac and associates in a retrospective case series analyzed data from 30,167 eyes from 16,732 documented ten eyes (0.033%) of seven patients that developed post-LASIK ectasia. This data supports the concept that the actual incidence of ectasia has decreased from 0.66% reported by Pallikaris in 2001. This has been the result of major development related to the advanced screening strategies. Nevertheless, mysterious cases of ectasia still challenge the field and stimulated research in this field. Ocular allergy and eye rubbing may be a factor that triggered ectasia in such series. Artificial intelligence (AI) and machine-learning algorithms may play a definitive role for further enhancing ectasia risk assessment. Reporting ectasia after LVC is needed.
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Affiliation(s)
- Renato Ambrósio
- a Department of Ophthalmology , Instituto de Olhos Renato Ambrósio , Rio de Janeiro , Brazil.,b Rio de Janeiro Corneal Tomography and Biomechanics Study Group , Rio de Janeiro , Brazil.,c Department of Ophthalmology , Federal University of São Paulo , São Paulo , Brazil.,d Department of Ophthalmology , Federal University of the State of Rio de Janeiro (UNIRIO) ; Rio de Janeiro , Brazil
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Moshirfar M, Motlagh MN, Murri MS, Momeni-Moghaddam H, Ronquillo YC, Hoopes PC. Advances in Biomechanical Parameters for Screening of Refractive Surgery Candidates: A Review of the Literature, Part III. MEDICAL HYPOTHESIS, DISCOVERY & INNOVATION OPHTHALMOLOGY JOURNAL 2019; 8:219-240. [PMID: 31598522 PMCID: PMC6778467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Corneal biomechanical properties have garnered significant interest in their relation to the development of ectatic corneal disease. Alongside the advent of corneal tomography and Scheimpflug imaging such as Pentacam and Galilei, there have been advances in assessing the cornea based on its biomechanical characteristics. Though the aforementioned imaging systems are highly capable of identifying morphologic abnormalities, they cannot assess mechanical stability of the cornea. This article, in contrast to Parts I and II of this article series, will focus on in vivo corneal biomechanical imaging systems. The two most readily available commercial systems include the Corvis ST and the Ocular Response Analyzer. Both of these systems aimed to characterize corneal biomechanics via distinct measurements. While in Parts I and II of this article series the authors focused on elevation, pachymetric, and keratometric data, the purpose of this article was to summarize biomechanical parameters and their clinical use in screening refractive surgery candidates. Moreover, this article explores biomechanical decompensation and its role in the development of corneal ectasia and keratoconus. There is a focus on the diagnostic accuracy of biomechanical indices in the identification of diseases such as keratoconus that may preclude a patient from undergoing refractive surgery.
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Affiliation(s)
- Majid Moshirfar
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, School of Medicine, University of Utah, Salt Lake City, UT, USA
- HDR Research Center, Hoopes Vision, Draper, UT, USA
| | - Mahsaw N. Motlagh
- Department of Ophthalmology, College of Medicine, University of Arizona, Tucson, AZ, USA
| | - Michael S. Murri
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, School of Medicine, University of Utah, Salt Lake City, UT, USA
| | - Hamed Momeni-Moghaddam
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
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Salomão M, Hoffling-Lima AL, Lopes B, Belin MW, Sena N, Dawson DG, Ambrósio R. Recent developments in keratoconus diagnosis. EXPERT REVIEW OF OPHTHALMOLOGY 2018. [DOI: 10.1080/17469899.2018.1555036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Marcella Salomão
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Instituto Benjamin Constant, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | | | - Bernardo Lopes
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Instituto Benjamin Constant, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
- Department of Biomaterial Mechanics, University of Liverpool, Liverpool, Tucson, UK
| | - Michael W. Belin
- Department of Ophthalmology and Visual Sciences, University of Arizona, USA
| | - Nelson Sena
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Daniel G. Dawson
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA
| | - Renato Ambrósio
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
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