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Salouti R, Azimi A, Meshksar A, Takapouy R, Ghoreyshi M, Salouti K, Razeghinejad R, Nowroozzadeh MH. Intraocular Pressure Before and After Corneal Refractive Surgery: A Prospective Comparison of Corvis ST and Ocular Response Analyzer. J Glaucoma 2024; 33:780-784. [PMID: 38767500 DOI: 10.1097/ijg.0000000000002434] [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: 11/18/2023] [Accepted: 04/13/2024] [Indexed: 05/22/2024]
Abstract
PRCIS The study showed that Corvis ST's biomechanical intraocular pressure (bIOP) and ocular response analyzer's (ORA) cornea-compensated intraocular pressure (IOPcc) do not agree well, before or after photorefractive keratectomy (PRK), and may not be used interchangeably. bIOP remained unchanged after PRK. OBJECTIVE To evaluate the agreement between the biomechanically corrected intraocular pressure (bIOP) measured by the Corvis ST and the IOPcc measured by the ORA before and after PRK. PATIENTS AND METHODS In this prospective interventional study, a total of 53 patients (53 eyes) were included. Measurements were acquired using both the Corvis ST and ORA devices before and 3 months post-PRK. The agreement between the 2 devices was evaluated using limits of agreement (LoA) and Bland-Altman plots. RESULTS The participants had a mean age of 29.6 ± 5.21 years (range: 21 to 40), with 41 (77.4%) of them being females. After the surgery, the average change in intraocular pressure (IOP) was 0.3 ± 1.7 mm Hg for bIOP and -1.6 ± 4.0 mm Hg for IOPcc. The corresponding 95% LoA were -3.5 to 4.2 mm Hg and -9.5 to 6.3 mm Hg, respectively. The 95% LoA between bIOP and IOPcc after PRK was -2.3 to 8.5 mm Hg. Notably, the bIOP values were higher for IOPs <20 mm Hg and lower for IOPs >20 mm Hg compared with IOPcc. CONCLUSIONS The findings indicate a weak agreement between the Corvis ST-bIOP and the ORA-IOPcc both before and after PRK. These devices may not be used interchangeably for IOP measurement. bIOP exhibited less variation compared with the IOPcc, suggesting that the bIOP may be a better option for IOP reading after PRK.
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Affiliation(s)
- Ramin Salouti
- Department of Ophthalmology, School of Medicine, Poostchi Ophthalmology Research Center, Shiraz University of Medical Sciences
- Salouti Cornea Research Center, Salouti Eye Clinic, Shiraz, Iran
| | - Ali Azimi
- Department of Ophthalmology, School of Medicine, Poostchi Ophthalmology Research Center, Shiraz University of Medical Sciences
| | - Aidin Meshksar
- Department of Ophthalmology, School of Medicine, Poostchi Ophthalmology Research Center, Shiraz University of Medical Sciences
| | - Ramin Takapouy
- Department of Ophthalmology, School of Medicine, Poostchi Ophthalmology Research Center, Shiraz University of Medical Sciences
| | - Maryam Ghoreyshi
- Salouti Cornea Research Center, Salouti Eye Clinic, Shiraz, Iran
| | - Kia Salouti
- Department of Science, The University of British Columbia, Vancouver, Canada
| | - Reza Razeghinejad
- Department of Ophthalmology, School of Medicine, Poostchi Ophthalmology Research Center, Shiraz University of Medical Sciences
- Glaucoma Service, Wills Eye Hospital, Philadelphia, PA
| | - Mohammad Hossein Nowroozzadeh
- Department of Ophthalmology, School of Medicine, Poostchi Ophthalmology Research Center, Shiraz University of Medical Sciences
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Niles CR, Crinzi AR, Bonaventura R, Taylor DA. Evaluation of agreement of IOP measurements by Tono-Vera tonometer to Goldmann applanation tonometry. FRONTIERS IN OPHTHALMOLOGY 2024; 4:1441343. [PMID: 39220349 PMCID: PMC11362087 DOI: 10.3389/fopht.2024.1441343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Accepted: 07/17/2024] [Indexed: 09/04/2024]
Abstract
Purpose To evaluate the accuracy of the new Tono-Vera rebound tonometer (Reichert Inc, Buffalo, NY) compared to Goldmann Applanation Tonometry. Methods This prospective, observational, cross-sectional study was designed in accordance with ANSI Z80.10-2014 and ISO 8612-2009 guidelines for tonometer comparison. Intraocular Pressure (IOP) was measured by Goldmann Applanation and Tono-Vera on 160 eyes of 160 subjects. Corneal Astigmatism and Central Corneal Thickness were also measured. A single investigator (CN) conducted all measurements. The average of two measurements from each tonometer was used in the analysis. Bland-Altman plots, total least squares regression analysis, and simple linear regression were used to evaluate agreement between the tonometers. Results Average IOP values from Goldmann Applanation and Tono-Vera were not significantly different (19.17 and 19.03 respectively, p=0.40, paired t-test). The total least squares regression analysis indicated strong agreement between the two tonometers (slope +0.97, offset +0.49 mmHg, standard deviation 2.11 mmHg). There were 2 IOP measurement pairs that exceeded the ± 5 mmHg limits of agreement required in ANSI Z80.10-2014 and ISO 8612-2009, which is within the range of acceptability specified in the standards. Conclusion We evaluated IOP measurements by Tono-Vera Rebound Tonometer vs Goldmann Applanation Tonometry for eyes with a wide range of IOP values and found no statistically significant differences in the results. Tono-Vera meets the requirements of ANSI Z80.10-2014 and ISO 8612-2009, demonstrating accuracy comparable to Goldmann tonometry.
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Affiliation(s)
- Charles R. Niles
- Ophthalmology Associates of WNY, Williamsville, NY, United States
| | - Alexander R. Crinzi
- Department of Ophthalmology, State University of New York at Buffalo, Buffalo, NY, United States
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Asaoka R, Aoki S, Fujino Y, Nakakura S, Murata H, Kiuchi Y. Comparing Corneal Biomechanic Changes between Solo Cataract Surgery and Microhook Ab Interno Trabeculotomy. J Clin Med 2024; 13:4564. [PMID: 39124830 PMCID: PMC11313163 DOI: 10.3390/jcm13154564] [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: 07/04/2024] [Revised: 07/20/2024] [Accepted: 07/31/2024] [Indexed: 08/12/2024] Open
Abstract
Background/Objectives: This study aimed to examine the postoperative changes in the corneal biomechanical properties between solo cataract surgery and solo microhook ab interno trabeculotomy (LOT). Methods: This retrospective case-control study included 37 eyes belonging to 26 patients who underwent solo cataract surgery and 37 eyes belonging to 31 patients who underwent solo µLOT. These two groups were matched according to their preoperative intraocular pressure (IOP), axial length (AL), and age. Corneal Visualization Scheimpflug Technology (Corvis ST) was used to obtain four biomechanical parameters representing the corneal stiffness or corneal deformation at the highest concavity, including stiffness parameter A1 (SP-A1), stress-strain index (SSI), peak distance (PD), and deflection amplitude max (DefAmpMax). These parameters were compared preoperatively and 6 months postoperatively, and between the two surgical groups. Results: Preoperatively, the patients' IOP, age, and AL, as well as their results in four Corvis ST parameters, were similar between the two groups (p > 0.05). No significant difference was observed in SP-A1; however, PD and DefAmpMax were significantly larger, and SSI was significantly smaller postoperatively in the LOT group than in the cataract group. Conclusions: Corneal stiffness was reduced, and the cornea was more deformed with LOT than cataract surgery.
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Affiliation(s)
- Ryo Asaoka
- Department of Ophthalmology, Seirei Hamamatsu General Hospital, Hamamatsu 430-0906, Shizuoka, Japan
- Seirei Christopher University, Hamamatsu 433-8558, Shizuoka, Japan
- The Graduate School for the Creation of New Photonics Industries, Hamamatsu 431-1202, Shizuoka, Japan
| | - Shuichiro Aoki
- Department of Ophthalmology, The University of Tokyo Graduate School of Medicine, Tokyo 113-0033, Japan
| | - Yuri Fujino
- Seirei Christopher University, Hamamatsu 433-8558, Shizuoka, Japan
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo 693-0021, Shimane, Japan
| | - Shunsuke Nakakura
- Department of Ophthalmology, Tsukazaki Memorial Hospital, Himeji 671-1227, Hyogo, Japan
| | - Hiroshi Murata
- Department of Ophthalmology, National Center for Global Health and Medicine, Shinjuku 162-8655, Tokyo, Japan
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima 739-0046, Hiroshima, Japan
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Shu N, He Y, Zhang Y. Research progress on measurement methods and clinical applications of corneal elastic modulus. Exp Eye Res 2024; 245:109974. [PMID: 38897271 DOI: 10.1016/j.exer.2024.109974] [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: 03/19/2024] [Revised: 06/07/2024] [Accepted: 06/16/2024] [Indexed: 06/21/2024]
Abstract
Various corneal diseases are strongly associated with corneal biomechanical characteristics, and early measurement of patients' corneal biomechanics can be utilized in their diagnosis and treatment. Measurement methods for corneal biomechanical characteristics are classified into ex vivo and in vivo. Some of these methods can directly measure certain corneal biomechanical parameters, while others require indirect calculation through alternative methods. However, due to diversities in measurement techniques and environmental conditions, significant differences may exist in the corneal mechanical properties measured by these two methods. Therefore, comprehensive research on current measurement methods and the exploration of novel measurement techniques may have great clinical significance. The corneal elastic modulus, a critical indicator in corneal biomechanics, reflects the cornea's ability to return to its initial shape after undergoing stress. This review aims to provide a comprehensive summary of the corneal elastic modulus, which is a critical biomechanical parameter, and discuss its direct, indirect, and potential measurement methods and clinical applications.
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Affiliation(s)
- Nanqi Shu
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130041, Jilin Province, China
| | - Yuxi He
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130041, Jilin Province, China
| | - Yan Zhang
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130041, Jilin Province, China; Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, China.
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Redaelli E, Calvo B, Rodriguez Matas JF, Luraghi G, Grasa J. Non-contact tonometry: predicting intraocular pressure using a material-corneal thickness-independent methodology. Front Bioeng Biotechnol 2024; 12:1406870. [PMID: 39119274 PMCID: PMC11306172 DOI: 10.3389/fbioe.2024.1406870] [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: 03/25/2024] [Accepted: 06/17/2024] [Indexed: 08/10/2024] Open
Abstract
Introduction: Glaucoma, a leading cause of blindness worldwide, is primarily caused by elevated intraocular pressure (IOP). Accurate and reliable IOP measurements are the key to diagnose the pathology in time and to provide for effective treatment strategies. The currently available methods for measuring IOP include contact and non contact tonometers (NCT), which estimate IOP based on the corneal deformation caused by an external load, that in the case of NCT is an air pulse. The deformation of the cornea during the tonometry is the result of the coupling between the IOP, the mechanical properties of the corneal tissue, the corneal thickness, and the external force applied. Therefore, there is the need to decouple the four contributions to estimate the IOP more reliably. Methods: This paper aims to propose a new methodology to estimate the IOP based on the analysis of the mechanical work performed by the air jet and by the IOP during the NCT test. A numerical eye model is presented, initially deformed by the action of a falling mass to study the energy balance. Subsequently, Fluid-Structure Interaction (FSI) simulations are conducted to simulate the action of Corvis ST. Results and discussion: The new IOP estimation procedure is proposed based on the results of the simulations. The methodology is centred on the analysis of the time of maximum apex velocity rather than the point of first applanation leading to a new IOP estimation not influenced by the geometrical and mechanical corneal factors.
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Affiliation(s)
- Elena Redaelli
- Aragón Institute of Engineering Research (I3A), Universidad de Zaragoza, Zaragoza, Spain
| | - Begoña Calvo
- Aragón Institute of Engineering Research (I3A), Universidad de Zaragoza, Zaragoza, Spain
- Centro de Investigación Biomecánica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, Spain
| | - Jose Felix Rodriguez Matas
- LaBS, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milan, Italy
| | - Giulia Luraghi
- LaBS, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milan, Italy
| | - Jorge Grasa
- Aragón Institute of Engineering Research (I3A), Universidad de Zaragoza, Zaragoza, Spain
- Centro de Investigación Biomecánica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, Spain
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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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Loveless BA, Moin KA, Hoopes PC, Moshirfar M. The Utilization of Brillouin Microscopy in Corneal Diagnostics: A Systematic Review. Cureus 2024; 16:e65769. [PMID: 39211657 PMCID: PMC11361473 DOI: 10.7759/cureus.65769] [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] [Accepted: 07/26/2024] [Indexed: 09/04/2024] Open
Abstract
Corneal biomechanical data has been used since 2005 to screen for keratoconus and corneal ectasia by corneal specialists. Older technology uses force applanation techniques over a 3 mm area in the central cornea, making it highly dependent on extraneous variables and unable to calculate the elasticity of the tissue. Brillouin microscopy is a newer method that uses a natural shift in the frequency of light as it passes through a material. This frequency shift can be used to estimate the viscoelasticity of the tissue. The advantage of Brillouin microscopy is that it can create a full three-dimensional (3D) map of the entire cornea without direct contact. A literature search was conducted using the databases PubMed, Google Scholar, and Ovid regarding the applications of Brillouin microscopy in corneal diagnostics. A final total of 16 articles was included describing the various ex vivo and in vivo studies conducted using Brillouin microscopy. Applications of this technology spanned from keratoconus diagnosis to post-corneal refractive surgery evaluation. All studies evaluated corneal biomechanics and other corneal properties through the quantification of Brillouin frequency shifts. Many of the studies found that this diagnostic device is capable of detecting subtle changes in corneal thickness and biomechanics in keratoconic corneas at a high level of specificity and sensitivity. However, limitations of Brillouin microscopy may include the duration of time required for use and fluctuations in accuracy depending on the corneal hydration state. Future technology seems to be geared toward a combination of optical coherence tomography (OCT) and Brillouin microscopy, using OCT as a three-dimensional pupil-tracking modality. Further research and understanding of the technology involved will lead to better care of patients in the field of ophthalmology.
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Affiliation(s)
- Bosten A Loveless
- Ophthalmology, Hoopes Vision Research Center, Draper, USA
- Ophthalmology, Rocky Vista University College of Osteopathic Medicine, Ivins, USA
| | - Kayvon A Moin
- Ophthalmology, Hoopes Vision Research Center, Draper, USA
- Ophthalmology, American University of the Caribbean School of Medicine, Cupecoy, SXM
| | | | - Majid Moshirfar
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, USA
- Ophthalmology, Hoopes Vision Research Center, Draper, USA
- Eye Banking and Corneal Transplantation, Utah Lions Eye Bank, Murray, USA
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Hamon L, Pfahl LJ, Flockerzi E, Berger T, Langenbucher A, Seitz B, Daas L. Implantation of Intracorneal Ring Segments in Keratectasia: Effects on Corneal Biomechanics in 112 Eyes. Cornea 2024; 43:702-709. [PMID: 37921596 DOI: 10.1097/ico.0000000000003419] [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: 05/18/2023] [Accepted: 09/24/2023] [Indexed: 11/04/2023]
Abstract
PURPOSE The aim of this study was to analyze changes in corneal biomechanical properties after implantation of intracorneal ring segments (ICRSs) in keratectasia. METHODS This retrospective single-center study included 112 patient eyes that underwent femtosecond laser-assisted ICRS implantation (Intacs SK; Addition Technology Inc, Des Plaines, IL) for keratectasia. Biomechanical analysis was performed using the Ocular Response Analyzer (ORA; Reichert Inc, Depew, NY), with determination of corneal resistance factor, corneal hysteresis, and Keratoconus Match Index, as well as by Corvis ST (OCULUS, Wetzlar, Germany), with determination of stiffness parameter A1, Ambrosio relational thickness to the horizontal profile (Arth), integrated radius, deformation amplitude ratio, and stress-strain index as well as Corvis Biomechanical Index and Tomographic Biomechanical Index. Data collection was performed preoperatively and 6 months postoperatively for ORA and Corvis ST and additionally after 1 and 2 years for ORA. RESULTS The corneal resistance factor decreased significantly postoperatively (5.8 ± 1.7 mm Hg) compared with preoperatively (6.75 ± 3.7 mm Hg; P = 0.021) and increased again during follow-up (6.2 ± 1.9 mm Hg; P = 0.024), without regaining preoperative values. Corneal hysteresis and Keratoconus Match Index did not change significantly. Stiffness parameter A1 ( P = 0.045) increased significantly after ICRS implantation and Arth decreased significantly from 181 ± 85 to 150 ± 92 ( P = 0.016). However, there was no significant postoperative change for others Corvis parameters. CONCLUSIONS Corneal biomechanical properties showed inconsistent changes after ICRS implantation. Classical corneal biomechanical parameters (using single central air-puff tonometers) do not seem to be suitable for follow-up after ICRS implantation.
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Affiliation(s)
- Loïc Hamon
- Department of Ophthalmology, Saarland University Medical Center (UKS), Homburg/Saar, Germany; and
| | - Luisa J Pfahl
- Department of Ophthalmology, Saarland University Medical Center (UKS), Homburg/Saar, Germany; and
| | - Elias Flockerzi
- Department of Ophthalmology, Saarland University Medical Center (UKS), Homburg/Saar, Germany; and
| | - Tim Berger
- Department of Ophthalmology, Saarland University Medical Center (UKS), Homburg/Saar, Germany; and
| | - Achim Langenbucher
- Institute for Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany
| | - Berthold Seitz
- Department of Ophthalmology, Saarland University Medical Center (UKS), Homburg/Saar, Germany; and
| | - Loay Daas
- Department of Ophthalmology, Saarland University Medical Center (UKS), Homburg/Saar, Germany; and
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Al Bdour M, Sabbagh HM, Jammal HM. Multi-modal imaging for the detection of early keratoconus: a narrative review. EYE AND VISION (LONDON, ENGLAND) 2024; 11:18. [PMID: 38730479 PMCID: PMC11088107 DOI: 10.1186/s40662-024-00386-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 04/21/2024] [Indexed: 05/12/2024]
Abstract
Keratoconus is a common progressive corneal disorder that can be associated with significant ocular morbidity. Various corneal imaging techniques have been used for the diagnosis of established cases. However, in the early stages of the disease, which include subclinical keratoconus and forme fruste keratoconus, detection of such cases can be challenging. The importance of detecting such cases is very important because early intervention can halt disease progression, improve visual outcomes and prevent postrefractive surgery ectasia associated with performing corneal refractive procedures in such patients. This narrative review aimed to examine several established and evolving imaging techniques for the detection of early cases of keratoconus. The utilization of combinations of these techniques may further increase their diagnostic ability.
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Affiliation(s)
- Muawyah Al Bdour
- Department of Ophthalmology, School of Medicine, The University of Jordan, Amman, Jordan
| | - Hashem M Sabbagh
- The National Center for Diabetes Endocrinology and Genetics (NCDEG), Amman, Jordan
| | - Hisham M Jammal
- Department of Ophthalmology, Faculty of Medicine, Jordan University of Science and Technology, PO Box 3030, Irbid, 22110, Jordan.
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Yii FS, He M, Chappell F, Bernabeu MO, MacGillivray T, Dhillon B, Tatham A, Strang N. Higher intraocular pressure is associated with slower axial growth in children with non-pathological high myopia. Eye (Lond) 2024; 38:1208-1214. [PMID: 38081936 PMCID: PMC11009290 DOI: 10.1038/s41433-023-02872-7] [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: 06/08/2023] [Revised: 11/21/2023] [Accepted: 11/23/2023] [Indexed: 04/13/2024] Open
Abstract
OBJECTIVES To investigate the association between intraocular pressure (IOP) and axial elongation rate in highly myopic children from the ZOC-BHVI High Myopia Cohort Study. METHODS 162 eyes of 81 healthy children (baseline spherical equivalent: -6.25 D to -15.50 D) aged 7-12 years with non-pathological high myopia were studied over five biennial visits. The mean (SD) follow-up duration was 5.2 (3.3) years. A linear mixed-effects model (LMM) was used to assess the association between IOP (at time point t-1) and axial elongation rate (annual rate of change in AL from t-1 to t), controlling for a pre-defined set of covariates including sex, age, central corneal thickness, anterior chamber depth and lens thickness (at t-1). LMM was also used to assess the contemporaneous association between IOP and axial length (AL) at t, controlling for the same set of covariates (at t) as before. RESULTS Higher IOP was associated with slower axial growth (β = -0.01, 95% CI -0.02 to -0.005, p = 0.001). There was a positive contemporaneous association between IOP and AL (β = 0.03, 95% CI 0.01-0.05, p = 0.004), but this association became progressively less positive with increasing age, as indicated by a negative interaction effect between IOP and age on AL (β = -0.01, 95% CI -0.01 to -0.003, p = 0.001). CONCLUSIONS Higher IOP is associated with slower rather than faster axial growth in children with non-pathological high myopia, an association plausibly confounded by the increased influence of ocular compliance on IOP.
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Affiliation(s)
- Fabian Sl Yii
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK.
- Curle Ophthalmology Laboratory, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh, UK.
| | - Mingguang He
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
- Centre for Eye Research Australia, The University of Melbourne, Melbourne, Australia
| | - Francesca Chappell
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
| | - Miguel O Bernabeu
- Centre for Medical Informatics, Usher Institute, The University of Edinburgh, Edinburgh, UK
- The Bayes Centre, The University of Edinburgh, Edinburgh, UK
| | - Tom MacGillivray
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
- Curle Ophthalmology Laboratory, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh, UK
| | - Baljean Dhillon
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
- Curle Ophthalmology Laboratory, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh, UK
- Princess Alexandra Eye Pavilion, NHS Lothian, Edinburgh, UK
| | - Andrew Tatham
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
- Princess Alexandra Eye Pavilion, NHS Lothian, Edinburgh, UK
| | - Niall Strang
- Department of Vision Sciences, Glasgow Caledonian University, Glasgow, UK
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11
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Komninou MA, Seiler TG, Enzmann V. Corneal biomechanics and diagnostics: a review. Int Ophthalmol 2024; 44:132. [PMID: 38478103 PMCID: PMC10937779 DOI: 10.1007/s10792-024-03057-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 02/16/2024] [Indexed: 03/17/2024]
Abstract
PURPOSE Corneal biomechanics is an emerging field and the interest into physical and biological interrelations in the anterior part of the eye has significantly increased during the past years. There are many factors that determine corneal biomechanics such as hormonal fluctuations, hydration and environmental factors. Other factors that can affect the corneas are the age, the intraocular pressure and the central corneal thickness. The purpose of this review is to evaluate the factors affecting corneal biomechanics and the recent advancements in non-destructive, in vivo measurement techniques for early detection and improved management of corneal diseases. METHODS Until recently, corneal biomechanics could not be directly assessed in humans and were instead inferred from geometrical cornea analysis and ex vivo biomechanical testing. The current research has made strides in studying and creating non-destructive and contactless techniques to measure the biomechanical properties of the cornea in vivo. RESULTS Research has indicated that altered corneal biomechanics contribute to diseases such as keratoconus and glaucoma. The identification of pathological corneas through the new measurement techniques is imperative for preventing postoperative complications. CONCLUSIONS Identification of pathological corneas is crucial for the prevention of postoperative complications. Therefore, a better understanding of corneal biomechanics will lead to earlier diagnosis of ectatic disorders, improve current refractive surgeries and allow for a better postoperative treatment.
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Affiliation(s)
- Maria Angeliki Komninou
- Department of Ophthalmology, Bern University Hospital Inselspital, University of Bern, Bern, Switzerland
- Institute of Intensive Care Medicine, University Hospital Zurich & University of Zurich, Zurich, Switzerland
| | - Theo G Seiler
- Department of Ophthalmology, Bern University Hospital Inselspital, University of Bern, Bern, Switzerland
- Klinik Für Augenheilkunde, Universitätsklinikum Düsseldorf, Düsseldorf, Germany
- Institut Für Refraktive Und Opthalmo-Chirurgie (IROC), Zurich, Switzerland
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Volker Enzmann
- Department of Ophthalmology, Bern University Hospital Inselspital, University of Bern, Bern, Switzerland.
- Department of BioMedical Research, University of Bern, Bern, Switzerland.
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12
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Karthikeyan SK, Sundaram SM, Ve RS, Souza DD, Biswas S, Shetty MU. Design and development of a noninvasive ocular pressure estimator. Optom Vis Sci 2024; 101:164-172. [PMID: 38546758 DOI: 10.1097/opx.0000000000002114] [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: 04/11/2024] Open
Abstract
SIGNIFICANCE A snapshot intraocular pressure (IOP) is ineffective in identifying the IOP peak and fluctuation, especially during sleep. Because IOP variability plays a significant role in the progression of glaucoma, monitoring the IOP, especially during sleep, is essential to capture the dynamic nature of IOP. PURPOSE We aimed to design an ocular pressure estimator (OPE) that can reliably and accurately measure the IOP noninvasively over closed-eyelid condition. METHODS Ocular pressure estimator works on the principle that the external pressure applied by raising the IOP of the eyeball is transmitted through a compressible septum to the pressure sensor, thus recording the IOP. A fluid-filled pouch with a pressure sensor was placed over a rubber glove mimicking the eyelid (septum), covering the cornea of enucleated goat eyeballs. A pressure-controlled setup was connected to a goat cadaver eye, which was validated by a rebound tonometer. Cannulation of eyeballs through the lower limbus had the least difference from the control setup values documented using rebound tonometer, compared with cannulation through the optic nerve. Intraocular pressures ranging from 3 to 30 mmHg was induced, and the outputs recorded using OPE were amplified and recorded for 10 minutes (n = 10 eyes). We stratified the randomization of the number of times and the induced pressures. RESULTS The measurements recorded were found to be linear when measured against an IOP range of 3 to 30 mmHg. The device has excellent reliability (intraclass correlation coefficient, 0.998). The repeatability coefficient and coefficient of variations were 4.24 (3.60 to 4.87) and 8.61% (7.33 to 9.90), respectively. The overall mean difference ± SD between induced IOP and the OPE was 0.22 ± 3.50 (95% confidence interval, -0.35 to 0.79) mmHg across all IOP ranges. CONCLUSIONS Ocular pressure estimator offers a promising approach for reliably and accurately measuring IOP and its fluctuation noninvasively under a condition mimicking a closed eye.
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Affiliation(s)
- Siddharth K Karthikeyan
- Department of Optometry, Manipal College of Health Professions (MCHP), Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - Swaminathan M Sundaram
- Department of Instrumentation and Control Engineering, Manipal Institute of Technology, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - Ramesh S Ve
- Department of Optometry, Manipal College of Health Professions (MCHP), Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - Donson D Souza
- Blackfrog Technologies Pvt Ltd, Manipal, Karnataka, India
| | - Sayantan Biswas
- Department of Optometry, Manipal College of Health Professions (MCHP), Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
- School of Optometry, College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - Mayur U Shetty
- Blackfrog Technologies Pvt Ltd, Manipal, Karnataka, India
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13
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Antonov AA, Volzhanin AV, Klinicheva EA, Karpilova MA. [Influence of corneal curvature and peripheral thickness on tonometry readings]. Vestn Oftalmol 2024; 140:43-50. [PMID: 38739130 DOI: 10.17116/oftalma202414002243] [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] [Indexed: 05/14/2024]
Abstract
PURPOSE This study investigates the influence of peripheral corneal thickness (PCT) and its curvature on tonometry readings. MATERIAL AND METHODS The study included 49 patients (49 eyes) who were indicated for glaucoma surgery. Using bidirectional applanation tonometry, the following parameters were obtained: IOPcc, IOPg - intraocular pressure (IOP) corrected for corneal compensation, taken as the most reliable indicator; IOP converted to Goldmann measurement, taken as the result of applanation tonometry, ΔIOP (IOPcc-IOPg), CH and CRF (corneal hysteresis and corneal resistance factor). During corneal topography, the corneal thickness was studied in the center, PCT at 1.5; 2, 3, 4 and 5 mm from the center in four meridians, as well as ΔPCT (PCT 3 mm - PCT 1.5 mm), the curvature of the anterior and posterior surfaces of the cornea and the depth of the anterior chamber. Aberrometry was used to obtain refractometry data and the curvature of the anterior surface of the cornea. The influence of the studied parameters on ΔIOP was evaluated. RESULTS ΔIOP correlated with CRF (r= -0.652), CH (r= -0.873), central corneal thickness (r= -0.293), PCT at all distances except 5 mm (r= -0.297; -0.287; -0.302; -0.303), with the strong and weak meridians of the anterior surface of the cornea (r=0.328; r=0.315), with the strong and weak meridians of the posterior surface, as well as the average curvature of the posterior surface (r=0.307; r=0.332; r=0.328). After step-by-step selection of the above parameters for creating a linear regression model for ΔIOP calculation, CH, CRF and PCT1.5mm remained in the model. The model describes ΔIOP with high accuracy (R2=0.974). CONCLUSION Biomechanical parameters of the cornea are the leading factor of applanation tonometry error. Individual linear dimensions of the cornea (thickness, curvature) have a lesser effect.
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Affiliation(s)
- A A Antonov
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - A V Volzhanin
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - E A Klinicheva
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - M A Karpilova
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
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14
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Del Barco O, Ávila FJ, Marcellán C, Remón L. Corneal retardation time as an ocular hypertension disease indicator. Biomed Phys Eng Express 2023; 10:015014. [PMID: 38055990 DOI: 10.1088/2057-1976/ad12fa] [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: 09/19/2023] [Accepted: 12/06/2023] [Indexed: 12/08/2023]
Abstract
Objective.A detailed analysis of the corneal retardation timeτas a highly related parameter to the intraocular pressure (IOP), and its plausible role as an indicator of ocular hypertension disease.Approach.A simple theoretical expression forτis derived within the corneal viscoelastic model of Kelvin-Voigt with 3 elements. This retardation time can be easily calculated from the well-known signal and pressure amplitudes of non-contact tonometers like the Ocular Response Analyzer (ORA). Then, a population-based study was performed where 100 subjects aged from 18 to 30 were analyzed (within this group, about 10% had an elevated IOP with more than 21 mmHg).Main results.A clear relationship between the corneal retardation time and the corneal-compensated intraocular pressure (IOPcc) was found, underlying the risk for ocular hypertensive (OHT) subjects with lowerτvalues to develop hypertension illnesses (due to the inability of poorly viscoelastic corneas to absorb IOP fluctuations, resulting in probable optic nerve damage).Significance.Our results might provide an useful tool to systematically discern which OHT patients (and even those with normal IOP values) are more likely to suffer glaucoma progression and, consequently, ensure an early diagnosis.
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Affiliation(s)
- Oscar Del Barco
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo, E-30100, Murcia, Spain
| | - Francisco J Ávila
- Departamento de Física Aplicada, Universidad de Zaragoza, E-50009, Zaragoza, Spain
| | - Concepción Marcellán
- Departamento de Física Aplicada, Universidad de Zaragoza, E-50009, Zaragoza, Spain
| | - Laura Remón
- Departamento de Física Aplicada, Universidad de Zaragoza, E-50009, Zaragoza, Spain
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15
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Desouky NA, Saafan MM, Mansour MH, Maklad OM. Patient-specific air puff-induced loading using machine learning. Front Bioeng Biotechnol 2023; 11:1277970. [PMID: 38026883 PMCID: PMC10663333 DOI: 10.3389/fbioe.2023.1277970] [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: 08/15/2023] [Accepted: 10/23/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction: The air puff test is a contactless tonometry test used to measure the intraocular pressure and the cornea's biomechanical properties. Limitations that most challenge the accuracy of the estimation of the corneal material and the intraocular pressure are the strong intercorrelation between the intraocular pressure and the corneal parameters, either the material properties that can change from one person to another because of age or the geometry parameters like central corneal thickness. This influence produces inaccuracies in the corneal deformation parameters while extracting the IOP parametric equation, which can be reduced through the consideration of the patient-specific air puff pressure distribution taking into account the changes in corneal parameters. This air puff pressure loading distribution can be determined precisely from the fluid-structure interaction (FSI) coupling between the air puff and the eye model. However, the computational fluid dynamics simulation of the air puff in the coupling algorithm is a time-consuming model that is impractical to use in clinical practice and large parametric studies. Methods: By using a supervised machine learning algorithm, we predict the time-dependent air puff pressure distribution for different corneal parameters via a parametric study of the corneal deformations and the gradient boosting algorithm. Results: The results confirmed that the algorithm gives the time-dependent air puff pressure distribution with an MAE of 0.0258, an RMSE of 0.0673, and an execution time of 93 s, which is then applied to the finite element model of the eye generating the corresponding corneal deformations taking into account the FSI influence. Using corneal deformations, the response parameters can be extracted and used to produce more accurate algorithms of the intraocular pressure and corneal material stress-strain index (SSI). Discussion: Estimating the distribution of air pressure on the cornea is essential to increase the accuracy of intraocular pressure (IOP) measurements, which serve as valuable indicator of corneal disease. We find that the air puff pressure loading is largely influenced by complex changes in corneal parameters unique to each patient case. With our innovative algorithm, we can preserve the same accuracy developed by the CFD-based FSI model, while reducing the computational time from approximately 101000 s (28 h) to 720 s (12 min), which is about 99.2% reduction in time. This huge improvement in computational cost will lead to significant improvement in the parametric equations for IOP and the Stress-Strain Index (SSI).
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Affiliation(s)
- Nada A. Desouky
- Mechanical Power Engineering Department, Faculty of Engineering, Mansoura University, Mansoura, Egypt
| | - Mahmoud M. Saafan
- Computers and Control Systems Engineering Department, Faculty of Engineering, Mansoura University, Mansoura, Egypt
| | - Mohamed H. Mansour
- Mechanical Power Engineering Department, Faculty of Engineering, Mansoura University, Mansoura, Egypt
| | - Osama M. Maklad
- Mechanical Power Engineering Department, Faculty of Engineering, Mansoura University, Mansoura, Egypt
- School of Engineering, Centre for Advanced Manufacturing and Materials, University of Greenwich, London, United Kingdom
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16
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Aoki S, Asaoka R, Fujino Y, Nakakura S, Murata H, Kiuchi Y. Comparing corneal biomechanic changes among solo cataract surgery, microhook ab interno trabeculotomy and iStent implantation. Sci Rep 2023; 13:19148. [PMID: 37932377 PMCID: PMC10628136 DOI: 10.1038/s41598-023-46709-5] [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: 03/10/2023] [Accepted: 11/03/2023] [Indexed: 11/08/2023] Open
Abstract
Minimally invasive glaucoma surgery has expanded the surgical treatment options in glaucoma, particularly when combined with cataract surgery. It is clinically relevant to understand the associated postoperative changes in biomechanical properties because they are influential on the measurement of intraocular pressure (IOP) and play an important role in the pathogenesis of open-angle glaucoma (OAG). This retrospective case-control study included OAG patients who underwent cataract surgery combined with microhook ab interno trabeculotomy (µLOT group: 53 eyes of 36 patients) or iStent implantation (iStent group: 59 eyes of 37 patients) and 62 eyes of 42 solo cataract patients without glaucoma as a control group. Changes in ten biomechanical parameters measured with the Ocular Response Analyzer and Corneal Visualization Scheimpflug Technology (Corvis ST) at 3 and 6 months postoperatively relative to baseline were compared among the 3 groups. In all the groups, IOP significantly decreased postoperatively. In the µLOT and control groups, significant changes in Corvis ST-related parameters, including stiffness parameter A1 and stress‒strain index, indicated that the cornea became softer postoperatively. In contrast, these parameters were unchanged in the iStent group. Apart from IOP reduction, the results show variations in corneal biomechanical changes from minimally invasive glaucoma surgery combined with cataract surgery.
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Affiliation(s)
- Shuichiro Aoki
- Department of Ophthalmology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
| | - Ryo Asaoka
- Department of Ophthalmology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan.
- Department of Ophthalmology, Seirei Hamamatsu General Hospital, 2-12-12 Sumiyoshi, Naka-Ku, Hamamatsu City, Shizuoka, Japan.
- Seirei Christopher University, Hamamatsu City, Shizuoka, Japan.
- The Graduate School for the Creation of New Photonics Industries, Hamamatsu City, Shizuoka, Japan.
| | - Yuri Fujino
- Department of Ophthalmology, Seirei Hamamatsu General Hospital, 2-12-12 Sumiyoshi, Naka-Ku, Hamamatsu City, Shizuoka, Japan
- Department of Ophthalmology, Shimane University Faculty of Medicine, Shimane, Japan
| | - Shunsuke Nakakura
- Department of Ophthalmology, Tsukazaki Memorial Hospital, Hyogo, Japan
| | - Hiroshi Murata
- Department of Ophthalmology, National Center for Global Health and Medicine, Tokyo, Japan
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima, Japan
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17
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Macedo M, Hatanaka M, Barboza WL, Mingione GM, Ambrósio R, Susanna R. The influence of topical anesthetic and fluorescein on non-contact tonometry measurements using ultra-high-speed dynamic Scheimpflug. Sci Rep 2023; 13:17864. [PMID: 37857798 PMCID: PMC10587345 DOI: 10.1038/s41598-023-45165-5] [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: 07/12/2023] [Accepted: 10/17/2023] [Indexed: 10/21/2023] Open
Abstract
This study aimed to investigate the effects of topical anesthetic and fluorescein drops on intraocular pressure (IOP), central corneal thickness (CCT) and biomechanical properties as measured by Corvis ST (CST-Oculus; Wezlar, Germany) in healthy eyes. A cross-sectional observational study was conducted on 46 healthy patients. The CST measurements were obtained before and immediately after the instillation of topical anesthetic and fluorescein drops. Pre-post instillation data were statistically analyzed. IOP measurements were compared to Goldmann's Applanation Tonometry (GAT), which was also performed after drops instillation. Biomechanical parameters analyzed included applanation 1 velocity, applanation 2 velocity, applanation 1 time, applanation 2 time, whole eye movement, deflection amplitude, and stiffness parameter at first applanation. A statistically significant difference in IOP, both for non-corrected IOP (IOPnct) and biomechanically corrected IOP (bIOP), was observed before and after the instillation of eyedrops. Despite this statistical significance, the observed difference lacked clinical relevance. The IOPnct demonstrated a significant difference pre and post-anesthetic and fluorescein instillation compared to GAT (14.99 ± 2.27 mmHg pre-instillation and 14.62 ± 2.50 mmHg post-instillation, versus 13.98 ± 2.04 mmHg, with p-values of 0.0014 and 0.0490, respectively). Comparable findings were noted when justaposing bIOP to GAT (14.53 ± 2.10 mmHg pre-instillation and 13.15 ± 2.25 mmHg post-instillation, against 13.98 ± 2.04 mmHg, with p-values of 0.0391 and 0.0022, respectively). Additionally, CCT measurements revealed a statistically significant elevation following the administration of topical anesthetic and fluorescein drops (from 544.64 ± 39.85 µm to 586.74 ± 41.71 µm, p < 0.01. None of the analyzed biomechanical parameters showed statistically significant differences after drops instillation. While the administration of topical anesthetic and fluorescein drops induced a statistically significant alteration in both IOPnct and bIOP readings, these changes were not clinically consequential. Furthermore, a notable statistical rise was observed in CCT measurements post-drops instillation, as determined by CST. Yet, corneal biomechanical parameters remained unaffected.
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Affiliation(s)
- Marcelo Macedo
- Department of Ophthalmology, University of São Paulo, São Paulo, Brazil.
| | - Marcelo Hatanaka
- Department of Ophthalmology, University of São Paulo, São Paulo, Brazil
| | | | | | - Renato Ambrósio
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Remo Susanna
- Department of Ophthalmology, University of São Paulo, São Paulo, Brazil
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18
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Jiménez-Santos M, Sáenz-Francés F, Rodríguez-Quet O, Cerván-Lopez I, Santos-Bueso E, Martinez-de-la-Casa JM, Jañez-Escalada L. Dependence of corneal hysteresis on non-central corneal thickness in healthy subjects. J Fr Ophtalmol 2023; 46:866-872. [PMID: 37085371 DOI: 10.1016/j.jfo.2022.12.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 12/18/2022] [Accepted: 12/20/2022] [Indexed: 04/23/2023]
Abstract
OBJECTIVE To evaluate the dependence of corneal hysteresis (CH) on non-central corneal thickness. METHODS Cross-sectional study of 1561 eyes of 1561 healthy volunteers with IOP less than 21mmHg, open angles on gonioscopy and no prior eye surgeries or local or systemic diseases. Pentacam-Scheimpflug technology was employed to segment the cornea into 6 circular zones centered on the apex (zones 1-6) and to determine the mean corneal thickness of these areas. CH was measured with ORA. Univariate and multivariate linear regression models adjusted for age and sex were created to model the dependence of CH on corneal thickness in zones 1 to 6. RESULTS In the univariate linear regression models, we found that CH was dependent on mean corneal thickness of zone 1 (B=0,004; R2=0.95%; P<0.001), zone 2 (B=0,004; R2=0.57%; P=0.002), zone 4 (B=0,005; R2=1.50%; P<0.001) and zone 6 (B=0,003; R2=0.92%; P<0.001). Similar results were obtained in the multivariate model (R2=3.46%; P<0.001). CONCLUSION This study suggests a significant dependence of CH on non-central corneal thickness. The model of corneal thickness segmentation into circular zones centered on the corneal apex is able to explain 3.47% of the variation in CH measurements.
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Affiliation(s)
- M Jiménez-Santos
- Ophthalmology Department, Hospital Clinico San Carlos, Madrid, Spain
| | - F Sáenz-Francés
- Ophthalmology Department, Hospital Clinico San Carlos, Madrid, Spain
| | - O Rodríguez-Quet
- Ophthalmology Department, Hospital Clinico San Carlos, Madrid, Spain.
| | - I Cerván-Lopez
- Centre d'ophthalmologie, Jardin des Buis, Carpentras, France
| | - E Santos-Bueso
- Ophthalmology Department, Hospital Clinico San Carlos, Madrid, Spain
| | | | - L Jañez-Escalada
- Instituto de Tecnología del Conocimiento, Universidad Complutense de Madrid, Madrid, Spain
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19
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Sánchez-Barahona C, Bolívar G, Teus MA. Comparison of Goldmann and ORA tonometers in newly diagnosed, untreated, POAG and OHT eyes. ARCHIVOS DE LA SOCIEDAD ESPANOLA DE OFTALMOLOGIA 2023; 98:528-532. [PMID: 37595792 DOI: 10.1016/j.oftale.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/12/2023] [Indexed: 08/20/2023]
Abstract
BACKGROUND AND OBJECTIVE The corneal biomechanical properties in naïve, untreated glaucoma and ocular hypertension (OHT) eyes is interesting, because it may be a source of error in intraocular pressure (IOP) measurements by Goldmann applanation tonometer (GAT) and Ocular Response Analyzer (ORA) The main objective of this study was to evaluate the IOP values obtained using GAT and the ORA, in primary open angle glaucoma (POAG) and in OHT untreated eyes. MATERIAL AND METHODS Observational, masked, cross sectional observational study. Newly diagnosed, untreated POAG and OHT eyes were included. RESULTS 51 POAG and 34 OHT eyes were analyzed. We found that IOPcc (IOP corneal-compensated) was significantly higher than GAT IOP in POAG (p = 0.0002) while we did not find any significant difference between both tonometers in OHT (p = 0.1). CONCLUSIONS GAT seems to underestimate the real IOP in untreated POAG eyes and it seems to be quite accurate in OHT eyes.
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Affiliation(s)
- C Sánchez-Barahona
- Departamento de Oftalmologia, Hospital General Universitario de Guadalajara, Guadalajara, Spain
| | - G Bolívar
- Departamento de Oftalmología, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, Spain; Departamento de Oftalmología, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain.
| | - M A Teus
- Departamento de Oftalmología, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, Spain; Departamento de Oftalmología, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
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20
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Hsia Y, Wei YH, Liao SL. The Changes in Ocular Biomechanical Response Parameters and Intraocular Pressure After Surgical Treatment for Thyroid Eye Disease. Invest Ophthalmol Vis Sci 2023; 64:31. [PMID: 37494009 PMCID: PMC10382999 DOI: 10.1167/iovs.64.10.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023] Open
Abstract
Purpose To investigate changes in ocular biomechanical response parameters and intraocular pressure (IOP) in patients with thyroid eye disease (TED) undergoing orbital decompression or anterior blepharotomy. Methods Eighty-three eyes from 46 patients receiving orbital decompression (the orbital decompression group) and 45 eyes from 28 patients receiving anterior blepharotomy (the anterior blepharotomy group) were retrospectively enrolled from a tertiary center. Corvis ST tonometry was used to assess ocular biomechanical response and biomechanically corrected IOP (bIOP) pre- and postoperatively. Non-contact tonometry (IOP-NCT) was also performed. Results In the anterior blepharotomy group, the margin reflex distance decreased (P < 0001). The highest concavity radius (P = 0.026) and whole eye movement (P = 0.003) increased. Neither IOP-NCT nor bIOP had a significant change. In the orbital decompression group, the extent of exophthalmos decreased (P < 0.001). The A2 length (P = 0.009) decreased. The bIOP did not show a significant change (16.4 ± 2.7 vs. 16.7 ± 4.5; P = 0.415), but the IOP-NCT decreased significantly (17.5 ± 3.3 vs. 16.0 ± 3.3; P < 0.001). Higher baseline IOP-NCT (β = -0.40, P < 0.001) and greater reduction in stiffness parameter A1 (SP-A1; β = 0.05, P = 0.002) were associated with more significant IOP-NCT reduction after the orbital decompression. Conclusions Ocular biomechanical response parameters may change after TED surgery, potentially affecting IOP measurements, particularly in patients receiving orbital decompression.
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Affiliation(s)
- Yun Hsia
- Department of Ophthalmology, National Taiwan University Hospital Hsin-Chu Branch, Hsinchu, Taiwan
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
| | - Yi-Hsuan Wei
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
- College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shu-Lang Liao
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
- College of Medicine, National Taiwan University, Taipei, Taiwan
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21
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Hein JC, Tauber J, Shrivastava A. Refractive surgery for the glaucoma suspect. Curr Opin Ophthalmol 2023; 34:290-295. [PMID: 36995100 DOI: 10.1097/icu.0000000000000954] [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: 03/31/2023]
Abstract
PURPOSE OF REVIEW The aim of this study was to provide an update on perioperative considerations in the evaluation and management of patients undergoing primary corneal and intraocular refractive procedures who are at risk for progressive glaucomatous optic neuropathy. RECENT FINDINGS The necessity of a comprehensive baseline assessment prior to refractive procedures with structural and functional testing, along with documentation of preoperative intraocular pressure (IOP) measurements, is highlighted in recent literature. Substantiation of the increased risk of postoperative IOP elevation in keratorefractive procedures in patients with higher baseline IOP and lower baseline CCT, but not necessarily the degree of myopia, has been variably evidenced. Tonometry methods which are less influenced by postoperative corneal structural change should be considered in patients undergoing keratorefractive procedures. Vigilence in postoperative monitoring for progressive optic neuropathy is suggested given evidence of an increased risk of steroid-response glaucoma in these patients. Additional evidence for the IOP-lowering impact of cataract surgery in patients with an increased risk of glaucoma is provided, irrespective of intraocular lens choice. SUMMARY Performing refractive procedures on patients at risk for glaucoma remains controversial. Definitive steps to optimize patient selection along with vigilance in disease state monitoring with longitudinal structural and functional testing can help mitigate potential adverse events.
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Affiliation(s)
| | - Jenna Tauber
- Montefiore Medical Center, New York City, New York, USA
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22
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Ma G, Cai J, Zhong R, He W, Ye H, Duvvuri C, Song C, Feng J, An L, Qin J, Huang Y, Xu J, Twa MD, Lan G. Corneal Surface Wave Propagation Associated with Intraocular Pressures: OCT Elastography Assessment in a Simplified Eye Model. Bioengineering (Basel) 2023; 10:754. [PMID: 37508781 PMCID: PMC10376591 DOI: 10.3390/bioengineering10070754] [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: 04/24/2023] [Revised: 06/18/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
Assessing corneal biomechanics in vivo has long been a challenge in the field of ophthalmology. Despite recent advances in optical coherence tomography (OCT)-based elastography (OCE) methods, controversy remains regarding the effect of intraocular pressure (IOP) on mechanical wave propagation speed in the cornea. This could be attributed to the complexity of corneal biomechanics and the difficulties associated with conducting in vivo corneal shear-wave OCE measurements. We constructed a simplified artificial eye model with a silicone cornea and controllable IOPs and performed surface wave OCE measurements in radial directions (54-324°) of the silicone cornea at different IOP levels (10-40 mmHg). The results demonstrated increases in wave propagation speeds (mean ± STD) from 6.55 ± 0.09 m/s (10 mmHg) to 9.82 ± 0.19 m/s (40 mmHg), leading to an estimate of Young's modulus, which increased from 145.23 ± 4.43 kPa to 326.44 ± 13.30 kPa. Our implementation of an artificial eye model highlighted that the impact of IOP on Young's modulus (ΔE = 165.59 kPa, IOP: 10-40 mmHg) was more significant than the effect of stretching of the silicone cornea (ΔE = 15.79 kPa, relative elongation: 0.98-6.49%). Our study sheds light on the potential advantages of using an artificial eye model to represent the response of the human cornea during OCE measurement and provides valuable insights into the impact of IOP on wave-based OCE measurement for future in vivo corneal biomechanics studies.
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Affiliation(s)
- Guoqin Ma
- School of Mechatronic Engineering and Automation, Foshan University, Foshan 528000, China
| | - Jing Cai
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528000, China
| | - Rijian Zhong
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528000, China
| | - Weichao He
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528000, China
| | - Haoxi Ye
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528000, China
| | | | - Chengjin Song
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528000, China
| | - Jinping Feng
- Institute of Engineering and Technology, Hubei University of Science and Technology, Xianning 437100, China
| | - Lin An
- Weiren Meditech Co., Ltd., Foshan 528000, China
| | - Jia Qin
- Weiren Meditech Co., Ltd., Foshan 528000, China
| | - Yanping Huang
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528000, China
- Weiren Meditech Co., Ltd., Foshan 528000, China
| | - Jingjiang Xu
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528000, China
- Weiren Meditech Co., Ltd., Foshan 528000, China
| | - Michael D. Twa
- College of Optometry, University of Houston, Houston, TX 77204, USA
| | - Gongpu Lan
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528000, China
- Weiren Meditech Co., Ltd., Foshan 528000, China
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23
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Zhang Q, Enikov ET. Prediction model of contact forces and IOP during digital palpation of porcine eyes. J Mech Behav Biomed Mater 2023; 142:105864. [PMID: 37141742 DOI: 10.1016/j.jmbbm.2023.105864] [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: 01/09/2023] [Revised: 04/11/2023] [Accepted: 04/16/2023] [Indexed: 05/06/2023]
Abstract
Frequent intraocular pressure (IOP) measurements are desirable in the diagnosis and management of glaucoma. Most current tonometers utilize some form of corneal deformation to estimate the IOP, since trans-scleral tonometry suffers from loss of sensitivity. Tran-scleral and trans-palpebral tonometry, however, offer a pathway towards a non-invasive home tonometry. This article presents a mathematical model capturing the relationship between the IOP and the displacements imposed onto the sclera by externally applied forces. Similar to manual digital palpation tonometry, trans-scleral mechanical palpation makes use of two force probes that are advanced in a specific order and distance. Data from the applied forces and displacements, along with concurrent measurements of IOP is used to produce a phenomenological mathematical model. The experiments were carried out on enucleated porcine eyes. Two models are presented. Model 1 predicts IOP vs forces and displacements, while Model 2 predicts the baseline IOP (prior to applying the forces) as a function of the measured forces and displacements. The proposed models result in IOP errors of 1.65 mmHG and 0.82 mmHg, respectively. Model parameters were extracted using least-squares-based system identification methods. The results show that the proposed models can be used to estimate the baseline IOP with accuracy of ±1 mmHg over a pressure range of 10-35 mmHg, solely from measurement of tactile forces and displacements.
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Affiliation(s)
- Qiuchen Zhang
- Advanced Micro- and Nanosystems Laboratory, Aerospace and Mechanical Engineering Department, University of Arizona, 1130 N Mountain Ave., Tucson, AZ 85721-0119, USA
| | - Eniko T Enikov
- Advanced Micro- and Nanosystems Laboratory, Aerospace and Mechanical Engineering Department, University of Arizona, 1130 N Mountain Ave., Tucson, AZ 85721-0119, USA.
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24
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Brazuna R, Alonso RS, Salomão MQ, Fernandes BF, Ambrósio R. Ocular Biomechanics and Glaucoma. Vision (Basel) 2023; 7:vision7020036. [PMID: 37218954 DOI: 10.3390/vision7020036] [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: 03/14/2023] [Revised: 04/11/2023] [Accepted: 04/21/2023] [Indexed: 05/24/2023] Open
Abstract
Biomechanics is a branch of biophysics that deals with mechanics applied to biology. Corneal biomechanics have an important role in managing patients with glaucoma. While evidence suggests that patients with thin and stiffer corneas have a higher risk of developing glaucoma, it also influences the accurate measurement of intraocular pressure. We reviewed the pertinent literature to help increase our understanding of the biomechanics of the cornea and other ocular structures and how they can help optimize clinical and surgical treatments, taking into consideration individual variabilities, improve the diagnosis of suspected patients, and help monitor the response to treatment.
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Affiliation(s)
- Rodrigo Brazuna
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro, Rio de Janeiro 22290-240, RJ, Brazil
| | - Ruiz S Alonso
- Department of Ophthalmology, Antonio Pedro University Hospital, Fluminense Federal University, Niterói 24033-900, RJ, Brazil
| | - Marcella Q Salomão
- Department of Ophthalmology, Federal University of São Paulo, São Paulo 04023-062, SP, Brazil
| | | | - Renato Ambrósio
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro, Rio de Janeiro 22290-240, RJ, Brazil
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25
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Lan G, Twa MD, Song C, Feng J, Huang Y, Xu J, Qin J, An L, Wei X. In vivo corneal elastography: A topical review of challenges and opportunities. Comput Struct Biotechnol J 2023; 21:2664-2687. [PMID: 37181662 PMCID: PMC10173410 DOI: 10.1016/j.csbj.2023.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 05/16/2023] Open
Abstract
Clinical measurement of corneal biomechanics can aid in the early diagnosis, progression tracking, and treatment evaluation of ocular diseases. Over the past two decades, interdisciplinary collaborations between investigators in optical engineering, analytical biomechanical modeling, and clinical research has expanded our knowledge of corneal biomechanics. These advances have led to innovations in testing methods (ex vivo, and recently, in vivo) across multiple spatial and strain scales. However, in vivo measurement of corneal biomechanics remains a long-standing challenge and is currently an active area of research. Here, we review the existing and emerging approaches for in vivo corneal biomechanics evaluation, which include corneal applanation methods, such as ocular response analyzer (ORA) and corneal visualization Scheimpflug technology (Corvis ST), Brillouin microscopy, and elastography methods, and the emerging field of optical coherence elastography (OCE). We describe the fundamental concepts, analytical methods, and current clinical status for each of these methods. Finally, we discuss open questions for the current state of in vivo biomechanics assessment techniques and requirements for wider use that will further broaden our understanding of corneal biomechanics for the detection and management of ocular diseases, and improve the safety and efficacy of future clinical practice.
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Affiliation(s)
- Gongpu Lan
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Michael D Twa
- College of Optometry, University of Houston, Houston, TX 77204, United States
| | - Chengjin Song
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
| | - JinPing Feng
- Institute of Engineering and Technology, Hubei University of Science and Technology, Xianning, Hubei 437100, China
| | - Yanping Huang
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Jingjiang Xu
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Jia Qin
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Lin An
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Xunbin Wei
- Biomedical Engineering Department, Peking University, Beijing 100081, China
- International Cancer Institute, Peking University, Beijing 100191, China
- Institute of Medical Technology, Peking University Health Science Center, Beijing 100191, China
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26
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Szurman P, Mansouri K, Dick HB, Mermoud A, Hoffmann EM, Mackert M, Weinreb RN, Rao HL, Seuthe AM. Safety and performance of a suprachoroidal sensor for telemetric measurement of intraocular pressure in the EYEMATE-SC trial. Br J Ophthalmol 2023; 107:518-524. [PMID: 34772665 PMCID: PMC10086291 DOI: 10.1136/bjophthalmol-2021-320023] [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] [Received: 07/06/2021] [Accepted: 10/18/2021] [Indexed: 11/04/2022]
Abstract
AIM To investigate the safety and performance of a telemetric suprachoroidal intraocular pressure (IOP) sensor (EYEMATE-SC) and the accuracy of its IOP measurements in open angle glaucoma (OAG) patients undergoing simultaneous non-penetrating glaucoma surgery (NPGS). METHODS Prospective, multicentre, open-label, single-arm, interventional clinical trial. Twenty-four eyes of 24 patients with OAG regularly scheduled for NPGS (canaloplasty or deep sclerectomy) were simultaneously implanted with an EYEMATE-SC sensor. Six-month follow-up on the sensor's safety and performance as well as on the level of agreement between the EYEMATE-SC measurements and IOP measurements with Goldmann applanation tonometry (GAT). RESULTS The eyes underwent canaloplasty (n=15) or deep sclerectomy (n=9) and achieved successful implantation of the sensor. No device migration, dislocation or serious device-related complications occurred. A total of 367 comparisons were included in the IOP agreement analysis. The overall mean difference between GAT and EYEMATE-SC measurements was 1.31 mm Hg (lower limit of agreement (LoA) 7.55 mm Hg; upper LoA -4.92 mm Hg). The maximum difference of 2.5 mm Hg ±3.96 (LoA 0.30-2.29) was reached on day 10 and continuously improved to an agreement of -0.15 mm Hg ±2.28 (LoA -1.24 to 0.89) after 6 months. Accordingly, the percentage of eyes within an IOP difference of ±5 mm Hg improved from 78% (day 3) to 100% (6 months). CONCLUSIONS After 6 months, the EYEMATE-SC sensor was safe and well tolerated, and allowed continual IOP monitoring. TRIAL REGISTRATION NUMBER NCT03756662.
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Affiliation(s)
- Peter Szurman
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, 66280 Sulzbach, Germany
| | - Kaweh Mansouri
- Glaucoma Research Centre, Montchoisi Hospital, Lausanne, Switzerland
| | - H Burkhard Dick
- Eye Clinic, University Hospital of the Ruhr University Bochum, Bochum, Germany
| | - Andre Mermoud
- Glaucoma Research Centre, Montchoisi Hospital, Lausanne, Switzerland
| | - Esther M Hoffmann
- Ophthalmology, University Medical Centre of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Marc Mackert
- Department of Ophthalmology, University Hospital, Ludwig-Maximilians-Universitat Munchen Medizinische Fakultat, Munich, Germany
| | - Robert N Weinreb
- Department of Ophthalmology at the Shiley Eye Institute, University of California at San Diego, La Jolla, California, USA
| | - Harsha Laxmana Rao
- Glaucoma, Narayana Nethralaya, Bangalore, India
- Ophthalmology, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Anna-Maria Seuthe
- Eye Clinic Sulzbach, Saar Knappschaft Hospital Sulzbach, Sulzbach, Germany
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27
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Hsu FLT, Shih PJ, Wang IJ. Development and validation of an intuitive biomechanics-based method for intraocular pressure measurement: a modal analysis approach. BMC Ophthalmol 2023; 23:124. [PMID: 36973657 PMCID: PMC10041475 DOI: 10.1186/s12886-023-02867-8] [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: 07/15/2022] [Accepted: 03/20/2023] [Indexed: 03/29/2023] Open
Abstract
BACKGROUND Current intraocular pressure (IOP) measurements based on non-contact tonometry are derived from statistics-driven equations and lack biomechanical significance, which often leads to under-estimation in post-refractive surgery cornea. This study aims to introduce and validate modal analysis-derived intraocular pressure (mIOP) as a novel method generated through Legendre-based modal decomposition of the anterior corneal contour; it provides an accurate and intuitive IOP measurement from an energy-based perspective. METHODS This retrospective study included 680 patients. Healthy participants were divided into reference (n = 385) and validation (n = 142) datasets, and the others underwent either femtosecond-assisted laser in situ keratomileusis (FS-LASIK, n = 58) or transepithelial photorefractive keratectomy (TPRK, n = 55). Corneal curvature of the right eyes was extracted from raw serial cross-sectional images of the cornea generated by Corvis ST, a noncontact tonometer with a high-speed Scheimpflug-camera. Legendre expansion was then applied to the corneal curvature to obtain the modal profiles (i.e., temporal changes of the coefficient for each basis polynomial [modes]). Using the reference dataset, feature selection on the modal profiles generated a final mIOP model consisting of a single parameter: total area under curve (frames 1-140) divided by the area under curve of the rising phase (frames 24-40) in the fourth mode, i.e. the M4 ratio. Validation was performed in both the healthy validation and postoperative datasets. IOP-Corvis, pachymetry-corrected IOP, biomechanically corrected IOP, and mIOP values were compared. For the FS-LASIK and TPRK groups, pairwise postoperative IOP changes were analyzed through repeated measures analysis of variance, and agreement was examined through Bland-Altman analysis. Using a finite element analysis based three-dimensional model of the human cornea, we further compared the M4 ratio with the true intraocular pressure within the physiological range. RESULTS The M4 ratio-based mIOP demonstrated weak to negligible association with age, radius of corneal curvature, and central corneal thickness (CCT) in all validation analyses, and performed comparably with biomechanically corrected IOP (bIOP) in the refractive surgery groups. Both remained nearly constant postoperatively and were not influenced by CCT changes. Additionally, M4 ratio accurately represented true intraocular pressure in the in silico model. CONCLUSIONS mIOP is a reliable IOP measurement in healthy and postrefractive surgery populations. This energy-based, ratio-derived approach effectively filters out pathological, rotational, misaligned movements and serves as an interpatient self-calibration index. Modal analysis of corneal deformation dynamics provides novel insights into regional corneal responses against pressure loading.
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Affiliation(s)
| | - Po-Jen Shih
- Department of Biomedical Engineering, National Taiwan University, 10048, Taipei, Taiwan.
| | - I-Jong Wang
- College of Medicine, National Taiwan University, 10048, Taipei, Taiwan
- Department of Ophthalmology, National Taiwan University Hospital, 10048, Taipei, Taiwan
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28
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Zhang Y, Bian A, Hang Q, Li L, Zhang S, Cheng G, Zhou Q. Corneal Biomechanical Properties of Various Types of Glaucoma and Their Impact on Measurement of Intraocular Pressure. Ophthalmic Res 2023; 66:749-756. [PMID: 36958304 PMCID: PMC10326840 DOI: 10.1159/000530291] [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: 07/01/2022] [Accepted: 03/10/2023] [Indexed: 03/25/2023]
Abstract
INTRODUCTION Corneal biomechanical properties could affect intraocular pressure (IOP) measurement. The aim of this study was to evaluate the differences in corneal biomechanical properties of various types of glaucoma, assess their effect on IOP measurements. METHODS This is an observational clinical study of 486 subjects including 102 normal subjects, 104 ocular hypertension (OHT), 89 normal tension glaucoma (NTG), and 191 high tension glaucoma (HTG). Corneal biomechanical parameters were measured using an ocular response analyzer. The main parameters assessed were corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated pressure measurement (IOPg), and corneal-compensated intraocular pressure (IOPcc). Ultrasound pachymetry was used to measure central corneal thickness (CCT). IOP was measured by a Goldmann applanation tonometer (GAT) and a noncontact tonometer (NCT). Visual field (VF) and refractive status were also recorded. Results were analyzed by one-way analysis of variance, univariate and multivariate linear regression analyses, and Bland-Altman plots. RESULTS Multiple comparison by analysis of variance showed significantly lower CH and CRF in NTG compared to HTG, OHT, and normal subjects (CH: 0.011, 0.015, and 0.033; CRF: 0.001, <0.001, and 0.042, respectively). CRF and CH associated with IOP were measured using either GAT, NCT and IOPcc-GAT, IOPcc-NCT, yet CCT was not. GAT correlated strongly with IOPg (r = 0.79; p < 0.001) and IOPcc (r = 0.77; p < 0.001), but limits of agreement between the measurements were poor. CH and CRF were both negatively correlated with VF change (p < 0.01). CONCLUSION CH and CRF affect the measurement of IOP and were related to types of glaucoma or severity of glaucoma. Pure CCT should not be used to correct IOP values or estimate the risk of disease.
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Affiliation(s)
- Yang Zhang
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China,
| | - Ailing Bian
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Qijun Hang
- Department of Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Lüe Li
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Shunhua Zhang
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Gangwei Cheng
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Qi Zhou
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
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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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EYEMATE-SC Trial: Twelve-Month Safety, Performance, and Accuracy of a Suprachoroidal Sensor for Telemetric Measurement of Intraocular Pressure. Ophthalmology 2023; 130:304-312. [PMID: 36202141 DOI: 10.1016/j.ophtha.2022.09.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 09/19/2022] [Accepted: 09/20/2022] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Measuring and controlling intraocular pressure (IOP) provide the foundation for glaucoma treatment. Self-tonometry has been proposed as an alternative to measure IOP throughout the entire day better. The novel EYEMATE-SC sensor (Implandata) is implanted in the suprachoroidal space to enable contactless continual IOP monitoring. The aim of the present study was to investigate the 1-year safety, performance, and accuracy of the EYEMATE-SC in patients with primary open-angle glaucoma undergoing simultaneous nonpenetrating glaucoma surgery (NPGS). DESIGN Prospective, multicenter, open-label, single-arm, interventional clinical trial. PARTICIPANTS Twenty-four eyes of 24 patients with primary open-angle glaucoma who were due to undergo NPGS (canaloplasty or deep sclerectomy). METHODS An EYEMATE-SC sensor was implanted during NPGS. Goldmann applanation tonometry (GAT) measurements were compared with the sensors' IOP measurements at all postoperative visits through 12 months. MAIN OUTCOME MEASURES Device position and adverse events. RESULTS Fifteen eyes underwent canaloplasty, and 9 underwent deep sclerectomy. Successful implantation of the sensor was achieved in all eyes with no reported intraoperative difficulties. Through the 12-month follow-up, no device migration, dislocation, or serious device-related complications were recorded. A total of 536 EYEMATE-SC measurements were pairwise included in the IOP agreement analysis. The overall mean difference between GAT and EYEMATE-SC measurements was 0.8 mmHg (95% confidence interval [CI] of the limits of agreement [LoA], -5.1 to 6.7 mmHg). The agreement gradually improved, and from 3 months after surgery until the end of the follow-up, the mean difference was -0.2 mmHg (95% CI of LoA, -4.6 to 4.2 mmHg) over a total of 264 EYEMATE-SC measurements, and 100% of measurements were within ±5 mmHg of GAT. CONCLUSIONS The EYEMATE-SC sensor was safe and well tolerated through 12 months. Moreover, it allowed accurate, continuous IOP monitoring. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.
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31
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Shen SR, Fleming GP, Jain SG, Roberts CJ. A Review of Corneal Biomechanics and Scleral Stiffness in Topical Prostaglandin Analog Therapy for Glaucoma. Curr Eye Res 2023; 48:172-181. [PMID: 35929977 DOI: 10.1080/02713683.2022.2099903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE The mechanism of action underlying prostaglandin analog (PGA) therapy involves changes in the expression of different metalloproteases to increase permeability of the sclera and allow increased aqueous humor outflow through this alternative drainage pathway. This alteration of structure impacts cornea/scleral biomechanics and may introduce artifact into the measurement of intraocular pressure (IOP) in the clinical setting. METHODS A literature search reviewing the impact of PGA therapy on corneal and scleral biomechanics was conducted including basic studies, clinical studies with treatment naïve patients, and a clinical study examining the cessation of PGA therapy. Additional literature including engineering texts was added for greater clarity of the concepts underlying ocular biomechanics. RESULTS One study with an animal model reported significant corneal stiffening with PGA treatment. Most longitudinal clinical studies examining the effects of initiation of PGA therapy in PGA naïve subjects failed to report biomechanical parameters associated with stiffness using the Corvis ST and only included those parameters strongly influenced by IOP. One study reported a significant reduction in scleral stiffness with IOP as a co-variate, highlighting the need to account for the effects of IOP lowering when assessing clinical biomechanics. The report of cessation of PGA therapy on corneal biomechanics showed no change in corneal compensated IOP after 6 weeks, raising the question of reversibility of the PGA-induced structural alteration. CONCLUSIONS Given that the findings in several clinical studies may merely reflect a reduction in IOP, further studies are warranted using Corvis ST parameters associated with corneal and scleral stiffness. The gold standard for IOP measurement in the clinical setting is Goldmann applanation tonometry, a technique previously shown to be affected by corneal stiffness. Since PGA therapy has been reported to alter not only scleral biomechanics, but also corneal biomechanics, it is essential to consider alternative tonometry technologies in the clinic.
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Affiliation(s)
- Steven R Shen
- College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Gloria P Fleming
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, USA
| | - Shelly Gupta Jain
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, USA
| | - Cynthia J Roberts
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
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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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33
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Li F, Wang K, Liu Z. In Vivo Biomechanical Measurements of the Cornea. BIOENGINEERING (BASEL, SWITZERLAND) 2023; 10:bioengineering10010120. [PMID: 36671692 PMCID: PMC9854753 DOI: 10.3390/bioengineering10010120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/18/2023]
Abstract
In early corneal examinations, the relationships between the morphological and biomechanical features of the cornea were unclear. Although consistent links have been demonstrated between the two in certain cases, these are not valid in many diseased states. An accurate assessment of the corneal biomechanical properties is essential for understanding the condition of the cornea. Studies on corneal biomechanics in vivo suggest that clinical problems such as refractive surgery and ectatic corneal disease are closely related to changes in biomechanical parameters. Current techniques are available to assess the mechanical characteristics of the cornea in vivo. Accordingly, various attempts have been expended to obtain the relevant mechanical parameters from different perspectives, using the air-puff method, ultrasound, optical techniques, and finite element analyses. However, a measurement technique that can comprehensively reflect the full mechanical characteristics of the cornea (gold standard) has not yet been developed. We review herein the in vivo measurement techniques used to assess corneal biomechanics, and discuss their advantages and limitations to provide a comprehensive introduction to the current state of technical development to support more accurate clinical decisions.
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Affiliation(s)
- Fanshu Li
- Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Health Science Center, Peking University, Beijing 100191, China
| | - Kehao Wang
- Beijing Advanced Innovation Center for Biomedical Engineering, School of Engineering Medicine, Beihang University, Beijing 100191, China
| | - Ziyuan Liu
- Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Health Science Center, Peking University, Beijing 100191, China
- Correspondence:
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Li J, Li C, Huang Y, Guan P, Huang D, Yu H, Yang X, Liu L. Mendelian randomization analyses in ocular disease: a powerful approach to causal inference with human genetic data. J Transl Med 2022; 20:621. [PMID: 36572895 PMCID: PMC9793675 DOI: 10.1186/s12967-022-03822-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 12/11/2022] [Indexed: 12/27/2022] Open
Abstract
Ophthalmic epidemiology is concerned with the prevalence, distribution and other factors relating to human eye disease. While observational studies cannot avoid confounding factors from interventions, human eye composition and structure are unique, thus, eye disease pathogenesis, which greatly impairs quality of life and visual health, remains to be fully explored. Notwithstanding, inheritance has had a vital role in ophthalmic disease. Mendelian randomization (MR) is an emerging method that uses genetic variations as instrumental variables (IVs) to avoid confounders and reverse causality issues; it reveals causal relationships between exposure and a range of eyes disorders. Thus far, many MR studies have identified potentially causal associations between lifestyles or biological exposures and eye diseases, thus providing opportunities for further mechanistic research, and interventional development. However, MR results/data must be interpreted based on comprehensive evidence, whereas MR applications in ophthalmic epidemiology have some limitations worth exploring. Here, we review key principles, assumptions and MR methods, summarise contemporary evidence from MR studies on eye disease and provide new ideas uncovering aetiology in ophthalmology.
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Affiliation(s)
- Jiaxin Li
- grid.412449.e0000 0000 9678 1884Department of Epidemiology, School of Public Health, China Medical University, Shenyang, Liaoning China
| | - Cong Li
- grid.413405.70000 0004 1808 0686Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 China
| | - Yu Huang
- grid.413405.70000 0004 1808 0686Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 China ,grid.413405.70000 0004 1808 0686Guangdong Cardiovascular Institute, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Peng Guan
- grid.412449.e0000 0000 9678 1884Department of Epidemiology, School of Public Health, China Medical University, Shenyang, Liaoning China
| | - Desheng Huang
- grid.412449.e0000 0000 9678 1884Department of Mathematics, School of Fundamental Sciences, China Medical University, Shenyang, Liaoning China
| | - Honghua Yu
- grid.413405.70000 0004 1808 0686Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 China
| | - Xiaohong Yang
- grid.413405.70000 0004 1808 0686Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 China
| | - Lei Liu
- grid.413405.70000 0004 1808 0686Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 China
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Ang RET, Rixon A, Kilgore K, Schweitzer J. Goldmann and modified Goldmann tonometry measuring intraocular pressure changes in eyes which underwent myopic laser in situ Keratomileusis and photorefractive keratectomy. BMC Ophthalmol 2022; 22:503. [PMID: 36539706 PMCID: PMC9768993 DOI: 10.1186/s12886-022-02741-z] [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: 10/09/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
PURPOSE Compare intraocular pressure (IOP) measured by a standard Goldmann applanation tonometer prism (IOPg) and a modified correcting applanation tonometer surface Goldmann prism (IOPc) before and after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). METHODS Goldmann tonometry was analyzed in a retrospective, cross-sectional study, using both GAT and modified-GAT prisms pre-operatively and at the 3 month post-operative appointment on 120 eyes (64 patients) who received LASIK (n = 58) or PRK (n = 62). Demographics, central corneal thickness (CCT), manifest refraction and corneal curvature (CC) data was collected at each visit as well as surgical parameters, including maximum ablation depth. RESULTS Mean paired IOP following LASIK decreased by - 3.28 ± 3.2 mmHg measured by IOPg and - 1.93 ± 3.3 mmHg by IOPc (p ≤ 0.0001). Mean paired IOP following PRK reduced by - 1.92 ± 3.6 mmHg measured by IOPg and - 1.06 ± 3.6 mmHg by IOPc (p ≤ 0.0001). Increased LASIK ablation depth and post-procedural change in CCT trended toward a statistically significant reduction in IOPg (p = 0.07,p = 0.12), but not IOPc (p = 0.18,p = 0.32). PRK ablation depth was not associated with a reduction in IOPg or IOPc. DISCUSSION The modified Goldmann (IOPc) prism measured less of an IOP reduction following LASIK and PRK compared to the standard (IOPg) prism, and the IOP reduction with both prisms was associated with the degree of myopic correction. WHAT IS ALREADY KNOWN AND THE RESIDUAL QUERY Corneal refractive surgery generally demonstrates significant postoperative Goldmann IOP reductions. Presumably, this is due to corneal biomechanical changes for which a newer method of Goldmann IOP measurement may be able to compensate. WHAT THIS STUDY ADDS A modified, corneal conforming Goldmann prism demonstrates significantly less IOP reduction following myopic LASIK and PRK compared to the standard flat Goldmann prism. HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY A newer, modified Goldmann prism may help detect glaucoma and OHT at an earlier stage in patients which have undergone LASIK or PRK. The findings corroborate predicted corneal biomechanical changes following the most common corneal refractive procedures.
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Affiliation(s)
- Robert Edward T. Ang
- Department of Ophthalmology, Cardinal Santos Medical Center, City, Metro Manila, San Juan, Philippines ,grid.476917.a0000 0004 9154 7342Cornea and Refractive Surgery Service, Asian Eye Institute, City, Metro Manila, Makati, Philippines ,grid.476917.a0000 0004 9154 7342Glaucoma Service, Asian Eye Institute, City, Metro Manila, Makati, Philippines
| | - Andrew Rixon
- grid.413847.d0000 0004 0420 4721Veterans Administration, Memphis, TN U.S.A.
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Shokrollahzadeh F, Hashemi H, Yekta A, Ostadimoghaddam H, Khabazkhoob M. Corneal Biomechanical Parameters after 60-Year-Old. J Curr Ophthalmol 2022; 34:284-289. [PMID: 36644461 PMCID: PMC9832466 DOI: 10.4103/joco.joco_201_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 01/08/2022] [Accepted: 01/12/2022] [Indexed: 12/09/2022] Open
Abstract
Purpose To determine the distribution of corneal biomechanical parameters in an elderly population. Methods This cross-sectional study was conducted in subjects above 60 years living in Tehran. The participants were selected using multi-stage cluster sampling. Corneal biomechanical parameters were measured in a randomly selected subsample of this population using the Reichert Ocular Response Analyzer (Reichert Ophthalmic Instruments, Inc., Buffalo, NY, USA). Results Of 470 subjects, the data of 420 participants aged over 60 years were analyzed (mean age: 69.3 ± 6.5 years and range: 61-88 years), 363 (86.4%) of whom were male. The mean and standard deviation of corneal hysteresis (CH) and corneal resistance factor (CRF) were 8.37 ± 1.55 mmHg (95% confidence interval [CI]: 8.02-8.72) and 9.06 ± 1.70 mmHg (95% CI: 8.69-9.44), respectively. The mean CH was 8.27 ± 1.54 mmHg in men and 9.25 ± 1.28 mmHg in women, and the mean CRF was 9.00 ± 1.71 mmHg in men and 9.63 ± 1.37 mmHg in women. According to the results of multiple linear logistic regression analysis, CH had a significant association with younger age (β = -0.05, P = 0.032), female sex (β = 1.83, P < 0.001), reduced maximum keratometry (β = -0.22, P = 0.06), and increased anterior chamber volume (β = 0.01, P = 0.007). CRF had a significant correlation with a younger age (β = -0.06, P = 0.02), female sex (β = 1.01, P = 0.05), central corneal thickness (β = 0.02, P < 0.001), and reduced maximum keratometry (β = -0.39, P = 0.010). Conclusion The mean CH and CRF values were low in this sample of the Iranian population aged over 60 years indicating the weaker elasticity of the corneal connective tissue.
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Affiliation(s)
- Fereshteh Shokrollahzadeh
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hassan Hashemi
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
| | - Abbasali Yekta
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran,Address for correspondence: Abbasali Yekta, Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran. E-mail:
| | - Hadi Ostadimoghaddam
- Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mehdi Khabazkhoob
- Department of Basic Sciences, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Yildiz I, Altan C, Çakmak S, Genc S, Yildirim Y, Agca A. Comparison of Intraocular Pressure Measurements With Goldmann Applanation Tonometry, Tonopen XL, and Pascal Dynamic Contour Tonometry in Patients With Descemet Membrane Endothelial Keratoplasty. J Glaucoma 2022; 31:909-914. [PMID: 35939831 DOI: 10.1097/ijg.0000000000002089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 07/17/2022] [Indexed: 02/04/2023]
Abstract
PRCIS IOP measured with Tonopen and DCT was higher than GAT in eyes that underwent DMEK. PURPOSE/AIM OF THE STUDY To compare intraocular pressure (IOP) measurements measured based on Goldmann applanation tonometry (GAT), Tonopen XL, and Pascal Dynamic Contour Tonometry (DCT) in patients who had undergone descemet membrane endothelial keratoplasty (DMEK) and to appraise the influence of central corneal thickness (CCT) on IOP measurements. MATERIALS AND METHODS Thirty-four eyes (from 34 patients) who underwent DMEK at least 1 month before the study were included. We performed Tonopen XL, GAT, and DCT IOP measurements at 10 min intervals. Bland-Altman plots were used to assess agreement between GAT, Tonopen XL, and DCT. Spearman rank correlation was used to calculate the deviation from GAT readings by each device and correlate the readings with the CCT variable. RESULTS The mean IOP values with GAT, Tonopen XL, and DCT were 14.9±5.8, 16.2±5.5, and 19.2±5.0, respectively. Statistically significant differences between GAT and Tonopen XL and between GAT and DCT were noted ( r =0.942 [0.885-0.971]; P =0.0001 and r =0.942 [0.885-0.971]; P =0.0001, respectively). DCT tended to return a higher IOP relative to GAT and Tonopen XL. CCT and IOP readings obtained by GAT, Tonopen XL, and DCT did not show a statistically significant correlation with each other. CONCLUSION IOP as measured with both Tonopen and DCT was found to be higher than GAT in eyes that underwent DMEK surgery although the techniques showed a good correlation. After DMEK surgery, all 3 measurement techniques can be practical in routine postoperative examinations, however it is recommended to measure IOP with the same device during patient follow-up.
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Affiliation(s)
- Izlem Yildiz
- University of Health Sciences, Beyoglu Eye Training and Research Hospital, Istanbul, Turkey
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Sk A, Adhikary P, Haldar PK. Nucleation of electro‐active β and γ‐phases in P(V
DF
−
HF
P) for manufacturing energy harvesting device and self powered weight measuring device. POLYM ENG SCI 2022. [DOI: 10.1002/pen.26152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Asadullah Sk
- Department of Physics Coochbehar Panchanan Barma University Cooch Behar West Bengal India
| | - Prakriti Adhikary
- Department of Physics University of North Bengal Darjeeling West Bengal India
| | - Prabir Kr. Haldar
- Department of Physics Coochbehar Panchanan Barma University Cooch Behar West Bengal India
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Kamalipour A, Moghimi S, Eslani M, Nishida T, Mohammadzadeh V, Micheletti E, Girkin CA, Fazio MA, Liebmann JM, Zangwill LM, Weinreb RN. A Prospective Longitudinal Study to Investigate Corneal Hysteresis as a Risk Factor of Central Visual Field Progression in Glaucoma. Am J Ophthalmol 2022; 240:159-169. [PMID: 35278360 PMCID: PMC10249485 DOI: 10.1016/j.ajo.2022.02.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/07/2022] [Accepted: 02/27/2022] [Indexed: 11/22/2022]
Abstract
PURPOSE To evaluate the role of corneal hysteresis (CH) as a risk factor of central visual field (VF) progression in a cohort of glaucoma suspect and glaucoma patients. DESIGN Prospective cohort study. METHODS Two hundred forty-eight eyes of 143 subjects who were followed for an average of 4.8 years with a minimum of 5 visits with 10-2 and 24-2 VF tests were included. Univariable and multivariable linear mixed-effects models were used to identify characteristics associated with the rate of change over time in 10-2 and 24-2 mean deviation (MD). Mixed-effects logistic regression was used to evaluate characteristics associated with an increased likelihood of event-based 10-2 VF progression based on the clustered pointwise linear regression criterion. RESULTS CH was significantly associated with 10-2 and 24-2 VF progression in the univariable trend-based analysis. In multivariable trend-based analyses, lower CH was associated with a faster rate of decline in 10-2 MD (0.07 dB/y per 1 mm Hg, P < .001) but not with 24-2 MD (P = .490). In multivariable event-based analysis, lower CH was associated with an increased likelihood of 10-2 VF progression (odds ratio = 1.35 per 1 mm Hg lower, P = .025). Similar results were found in eyes with early glaucomatous damage at the baseline (baseline: 24-2 MD ≥ -6 dB). CONCLUSIONS Lower CH was associated with a statistically significant, but relatively small, increased risk of central VF progression on the 10-2 test grid. Given the substantial influence of central VF impairment on the quality of life, clinicians should consider using CH to assess the risk of progression in patients with primary open-angle glaucoma including those with early disease.
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Affiliation(s)
- Alireza Kamalipour
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California
| | - Sasan Moghimi
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California
| | - Medi Eslani
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California
| | - Takashi Nishida
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California
| | - Vahid Mohammadzadeh
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California
| | - Eleonora Micheletti
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California
| | | | - Massimo A Fazio
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California; Department of Ophthalmology and Visual Sciences, Heersink School of Medicine; Department of Biomedical Engineering, School of Engineering
| | - Jeffrey M Liebmann
- University of Alabama at Birmingham, Alabama, and Bernard and Shirlee Brown Glaucoma Research Laboratory, Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, New York, USA
| | - Linda M Zangwill
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California
| | - Robert N Weinreb
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California.
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Effect of prostaglandin analogues on the biomechanical corneal properties in patients with open-angle glaucoma and ocular hypertension measured with dynamic scheimpflug analyzer. Graefes Arch Clin Exp Ophthalmol 2022; 260:3927-3933. [PMID: 35841397 DOI: 10.1007/s00417-022-05752-0] [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: 03/24/2022] [Revised: 06/18/2022] [Accepted: 06/29/2022] [Indexed: 11/04/2022] Open
Abstract
PURPOSE The aim of the study is to evaluate the effect of topical prostaglandin (PG) treatment on the corneal biomechanical properties in treatment-naïve patients with either primary open-angle glaucoma (POAG) or ocular hypertension (OHT) using the Corvis ST device. METHODS This is an observational study. We analyzed the Corvis ST dynamic corneal response parameters of our database using the newest software available. Thirty-four eyes of 34 patients were included. They were all newly diagnosed and treatment-naïve. Patients were evaluated at baseline and after 6 months of treatment with prostaglandin analogues. Ultrasound pachymetry, Optical Coherence Tomography (OCT) and a 24-2 visual field test were performed in baseline visit. Goldman Applanation Tonometry (GAT-IOP) and Corvis ST dynamic corneal response parameters were registered at baseline and at the 6-month visit. RESULTS After 6 months of treatment, the IOP decrease (Δ) values obtained with the different tonometers were ΔGAT -6.5 ± 3.7, ΔIOPnct -4.4 ± 5.7 and ΔbIOP -3.8 ± 5.4. The differences between ΔGAT vs ΔIOPnct, ΔGAT vs ΔbIOP, and ΔIOPnct vs ΔbIOP, were statistically significant (p < 0.05 for all comparisons). Statistically significant lower values of the stress-strain index (SSI) (1.77 ± 0.3 at baseline vs 1.54 ± 0.27 at the 6-month visit) were found (p = 0.0002). CONCLUSION The SSI provided by the Corvis ST seems to decrease significantly after topical prostaglandin therapy. We believe that our results support the hypothesis that topical PG therapy does decrease the corneal stiffness and thus, that the ocular hypotensive effect of these drugs is overestimated if GAT is used for IOP measurement.
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Hua Y, Lu Y, Walker J, Lee PY, Tian Q, McDonald H, Pallares P, Ji F, Brazile BL, Yang B, Voorhees AP, Sigal IA. Eye-specific 3D modeling of factors influencing oxygen concentration in the lamina cribrosa. Exp Eye Res 2022; 220:109105. [PMID: 35568202 PMCID: PMC11007759 DOI: 10.1016/j.exer.2022.109105] [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: 12/21/2021] [Revised: 04/06/2022] [Accepted: 04/28/2022] [Indexed: 11/29/2022]
Abstract
Our goal was to identify the factors with the strongest influence on the minimum lamina cribrosa (LC) oxygen concentration as potentially indicative of conditions increasing hypoxia risk. Because direct measurement of LC hemodynamics and oxygenation is not yet possible, we developed 3D eye-specific LC vasculature models. The vasculature of a normal monkey eye was perfusion-labeled post-mortem. Serial cryosections through the optic nerve head were imaged using fluorescence and polarized light microscopy to visualize the vasculature and collagen, respectively. The vasculature within a 450 μm-thick region containing the LC - identified from the collagen, was segmented, skeletonized, and meshed for simulations. Using Monte Carlo sampling, 200 vascular network models were generated with varying vessel diameter, neural tissue oxygen consumption rate, inflow hematocrit, and blood pressures (arteriole, venule, anterior boundary, and posterior boundary). Factors were varied over ranges of baseline ±20% with uniform probability. For each model we first obtained the blood flow, and from this the neural tissue oxygen concentration. ANOVA was used to identify the factors with the strongest influence on the minimum (10th percentile) oxygen concentration in the LC. The three most influential factors were, in ranked order, vessel diameter, neural tissue oxygen consumption rate, and arteriole pressure. There was a strong interaction between vessel diameter and arteriole pressure whereby the impact of one factor was larger when the other factor was small. Our results show that, for the eye analyzed, conditions that reduce vessel diameter, such as vessel compression due to elevated intraocular pressure or gaze-induced tissue deformation, may particularly contribute to decreased LC oxygen concentration. More eyes must be analyzed before generalizing.
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Affiliation(s)
- Yi Hua
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Yuankai Lu
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Jason Walker
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA, United States
| | - Po-Yi Lee
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Qi Tian
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Haiden McDonald
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA, United States
| | - Pedro Pallares
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA, United States
| | - Fengting Ji
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Bryn L Brazile
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Bin Yang
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States; Department of Engineering, Rangos School of Health Sciences, Duquesne University, Pittsburgh, PA, United States
| | - Andrew P Voorhees
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Ian A Sigal
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States.
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Nishida T, Kojima T, Kataoka T, Isogai N, Yoshida Y, Nakamura T. Evaluation of the Relationship Between the Changes in the Corneal Biomechanical Properties and Changes in the Anterior Segment OCT Parameters Following Customized Corneal Cross-Linking. Clin Ophthalmol 2022; 16:1909-1923. [PMID: 35711971 PMCID: PMC9192785 DOI: 10.2147/opth.s361836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/12/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose Patients and Methods Results Conclusion
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Affiliation(s)
| | - Takashi Kojima
- Nagoya Eye Clinic, Nagoya, Japan
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
- Correspondence: Takashi Kojima, Department of Ophthalmology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo, Japan, Tel +81-3-5363-2012, Fax +81-3-3359-7027, Email
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Karimi A, Razaghi R, Rahmati SM, Downs JC, Acott TS, Wang RK, Johnstone M. Modeling the biomechanics of the conventional aqueous outflow pathway microstructure in the human eye. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 221:106922. [PMID: 35660940 PMCID: PMC10424784 DOI: 10.1016/j.cmpb.2022.106922] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/16/2022] [Accepted: 05/26/2022] [Indexed: 05/27/2023]
Abstract
BACKGROUND AND OBJECTIVE Intraocular pressure (IOP) is determined by aqueous humor outflow resistance, which is a function of the combined resistance of Schlemm's canal (SC) endothelium and the trabecular meshwork (TM) and their interactions in the juxtacanalicular connective tissue (JCT) region. Aqueous outflow in the conventional outflow pathway results in pressure gradient across the TM, JCT, and SC inner wall, and induces mechanical stresses and strains that influence the geometry and homeostasis of the outflow system. The outflow resistance is affected by alteration in tissues' geometry, so there is potential for active, two-way, fluid-structure interaction (FSI) coupling between the aqueous humor (fluid) and the TM, JCT, and SC inner wall (structure). However, our understanding of the biomechanical interactions of the aqueous humor with the outflow connective tissues and its contribution to the outflow resistance regulation is incomplete. METHODS In this study, a microstructural finite element (FE) model of a human eye TM, JCT, and SC inner wall was constructed from a segmented, high-resolution histologic 3D reconstruction of the human outflow system. Three different elastic moduli (0.004, 0.128, and 51.5 MPa based on prior reports) were assigned to the TM/JCT complex while the elastic modulus of the SC inner wall was kept constant at 0.00748 MPa. The hydraulic conductivity was programmed separately for the TM, JCT, and SC inner wall using a custom subroutine. Cable elements were embedded into the TM and JCT extracellular matrix to represent the directional stiffness imparted by anisotropic collagen fibril orientation. The resultant stresses and strains in the outflow system were calculated using fluid-structure interaction method. RESULTS The higher TM/JCT stiffness resulted in larger stresses, but smaller strains in the outflow connective tissues, and resulted in a 4- and 5-fold larger pressure drop across the SC inner wall, respectively, compared to the most compliant model. Funneling through µm-sized SC endothelial pores was evident in the models at lower tissue stiffness, but aqueous flow was more turbulent in models with higher TM/JCT stiffness. CONCLUSIONS The mechanical properties of the outflow tissues play a crucial role in the hydrodynamics of the aqueous humor in the conventional outflow system.
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Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, 1670 University Boulevard, VH 372B, Birmingham, AL 35294, USA.
| | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, 1670 University Boulevard, VH 372B, Birmingham, AL 35294, USA
| | | | - J Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, 1670 University Boulevard, VH 372B, Birmingham, AL 35294, USA
| | - Ted S Acott
- Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Ruikang K Wang
- Department of Ophthalmology, University of Washington, Seattle, WA, USA; Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
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44
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Wu N, Chen Y, Sun X. Association Between Ocular Biomechanics Measured With Corvis ST and Glaucoma Severity in Patients With Untreated Primary Open Angle Glaucoma. Transl Vis Sci Technol 2022; 11:10. [PMID: 35679036 PMCID: PMC9187943 DOI: 10.1167/tvst.11.6.10] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To compare the ocular biomechanical differences between normal controls and patients with untreated primary open angle glaucoma, including normal-tension glaucoma (NTG) and high-tension glaucoma (HTG), and to investigate the association between ocular biomechanics and glaucoma severity in each group. Methods One hundred fifty-three eyes of 153 subjects, including 51 controls, 47 NTG, and 55 HTG cases, were enrolled in this cross-sectional study. Each participant underwent biomechanical measurements by using the Corneal Visualization Scheimpflug Technology. Glaucoma severity was evaluated by mean deviation (MD), pattern standard deviation (PSD), ganglion cell complex (GCC), and retinal nerve fiber layer (RNFL) thickness. Results Deformation amplitude (P = 0.001) significantly increased, whereas first applanation time (P < 0.0001), highest concavity time (P = 0.001), stiffness parameter at first applanation (P = 0.009), and time of whole eye movement (WEM, P = 0.008) decreased significantly in NTG eyes compared with controls. Besides, NTG had the highest first applanation velocity than controls (P < 0.0001) and HTG (P = 0.044). Shorter time of WEM was independently correlated with worse MD (P = 0.02) and higher values of PSD (P = 0.03) in NTG. Axial length was positively related to PSD (P = 0.02) and negatively related to GCC (P < 0.0001) and RNFL (P < 0.0001) thickness in HTG. Conclusions NTG corneas are more deformable than healthy ones and HTG. Time of WEM, which relates to orbital compliance, is significantly associated with glaucomatous visual field defect in NTG, whereas axial length is correlated with glaucoma severity in HTG. Translational Relevance Ocular biomechanics may partly account for the differences of pathogenic mechanisms between NTG and HTG.
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Affiliation(s)
- Na Wu
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China
| | - Yuhong Chen
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China
| | - Xinghuai Sun
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China.,State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
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45
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Brazuna R, Salomão M, Esporcatte B, Macedo M, Esporcatte L, Colombini GNUI, Ambrósio R. Corneal biomechanics and glaucoma beyond the bidirectional impact of intraocular pressure and corneal deformation response. REVISTA BRASILEIRA DE OFTALMOLOGIA 2022. [DOI: 10.37039/1982.8551.20220036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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46
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Ang RET, Bargas NVR, Martinez GHA, Sosuan GMN, Nabor-Umali MI. Comparison of Three Tonometers in Measuring Intraocular Pressure in Eyes That Underwent Myopic Laser in situ Keratomileusis and Photorefractive Keratectomy. Clin Ophthalmol 2022; 16:1623-1637. [PMID: 35656390 PMCID: PMC9153993 DOI: 10.2147/opth.s362344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/16/2022] [Indexed: 11/23/2022] Open
Abstract
Objective Methods Results Conclusion
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Affiliation(s)
- Robert Edward T Ang
- Department of Ophthalmology, Cardinal Santos Medical Center, San Juan City, Metro Manila, Philippines
- Cornea and Refractive Surgery Service, Asian Eye Institute, Makati City, Metro Manila, Philippines
- Glaucoma Service, Asian Eye Institute, Makati City, Metro Manila, Philippines
- Correspondence: Robert Edward T Ang, Cornea and Refractive Surgery and Glaucoma Services, Asian Eye Institute, Makati City, Metro Manila, Philippines, Email
| | - Neiman Vincent R Bargas
- Department of Ophthalmology, Cardinal Santos Medical Center, San Juan City, Metro Manila, Philippines
| | - Gladness Henna A Martinez
- Department of Ophthalmology, Cardinal Santos Medical Center, San Juan City, Metro Manila, Philippines
| | | | - Maria Isabel Nabor-Umali
- Cornea and Refractive Surgery Service, Asian Eye Institute, Makati City, Metro Manila, Philippines
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47
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Ocular biomechanics during improvised explosive device blast: A computational study using eye-specific models. Injury 2022; 53:1401-1415. [PMID: 35144807 PMCID: PMC8940691 DOI: 10.1016/j.injury.2022.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/27/2022] [Accepted: 02/03/2022] [Indexed: 02/02/2023]
Abstract
BACKGROUND Eye injuries comprise 10-13% of civilian improvised explosive device (IED) injuries. The bomb blast wave induces a normal and shear forces on the tissues, causing a large acute IOP elevation. This study calculated the biomechanical stresses and strains in the eye due to IED explosion via eye-specific fluid-structure interaction (FSI) models. METHODS Blast occurred at 2, 3, and 4 m from the front and side of the victim and the weights of the IED were 1 and 2 kg. The ground was covered with the deformable soil to mimic the realistic IED explosion condition and reflect the blast wave. RESULTS The IOP elevation of ∼6,000-48,000 mmHg was observed in the eyes while the highest IOP was occurred with the IED weight and distance of 2 kg and 2 m (front) and the lowest was occurred with the IED weight and distance of 1 kg and 4 m (side). Our findings suggest the importance of the victim location and orientation concerning the blast wave when it comes to ocular injury assessment. IOP elevation of ∼2900 and ∼2700 mmHg were observed in ∼1.6 ms after the blast for the IEDS weight of 2 kg and a victim distance of 2 m in front and side blasts, respectively, in consistence with the literature. Nonetheless, IOPs were considerably higher after ∼1.6 ms due to the merging of the bomb blast wave and its reflection off the ground. CONCLUSIONS The stresses and strains were highest for the frontal blast. Both side and frontal blasts caused higher stresses and strains at the rectus muscle insertions where the sclera is thinnest and prone to rupture. Blast angle has no considerable role in the resultant IOP. Front blast with a heavier IED resulted a higher stresses and deformations in the eye connective tissues compared to the side blast.
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48
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Muench S, Roellig M, Balzani D. A new method for the in vivo identification of degenerated material property ranges of the human eye: feasibility analysis based on synthetic data. Biomech Model Mechanobiol 2022; 21:401-418. [PMID: 34928468 PMCID: PMC8940849 DOI: 10.1007/s10237-021-01541-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 11/24/2021] [Indexed: 11/25/2022]
Abstract
This paper proposes a new method for in vivo and almost real-time identification of biomechanical properties of the human cornea based on non-contact tonometer data. Further goal is to demonstrate the method's functionality based on synthetic data serving as reference. For this purpose, a finite element model of the human eye is constructed to synthetically generate full-field displacements from different data sets with keratoconus-like degradations. Then, a new approach based on the equilibrium gap method combined with a mechanical morphing approach is proposed and used to identify the material parameters from virtual test data sets. In a further step, random absolute noise is added to the virtual test data to investigate the sensitivity of the new approach to noise. As a result, the proposed method shows a relevant accuracy in identifying material parameters based on full-field displacements. At the same time, the method turns out to work almost in real time (order of a few minutes on a regular workstation) and is thus much faster than inverse problems solved by typical forward approaches. On the other hand, the method shows a noticeable sensitivity to rather small noise amplitudes rendering the method not accurate enough for the precise identification of individual parameter values. However, analysis show that the accuracy is sufficient for the identification of property ranges which might be related to diseased tissues. Thereby, the proposed approach turns out promising with view to diagnostic purposes.
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Affiliation(s)
- Stefan Muench
- Department of Testing of Electronics and Optical Methods, Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Dresden, Germany
| | - Mike Roellig
- Department of Testing of Electronics and Optical Methods, Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Dresden, Germany
| | - Daniel Balzani
- Chair of Continuum Mechanics, Ruhr University Bochum, Bochum, Germany.
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Yaghoubi V, Setayeshnasab H, Mosaddegh P, Kadkhodaei M. A stochastic approach to estimate intraocular pressure and dynamic corneal responses of the cornea. J Mech Behav Biomed Mater 2022; 130:105210. [PMID: 35397406 DOI: 10.1016/j.jmbbm.2022.105210] [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: 08/29/2021] [Revised: 03/17/2022] [Accepted: 03/26/2022] [Indexed: 11/15/2022]
Abstract
IntraOcular Pressure (IOP) is one of the most informative factors for monitoring the eye-health. This is usually measured by tonometers. However, the outputs of the tonometers depend on the physical and geometrical properties of the cornea. Therefore, the common practice is to develop a numerical model to generate some correction factors. The main challenge here is the accuracy and efficiency of a numerical model in predicting the IOP and Dynamic Corneal Response (DCR) of each patient. This study addresses this issue by developing a two-step surrogate model based on adaptive sparse Polynomial Chaos Expansion (PCE) for fast and accurate prediction of the IOP. In this regard, first, an FE model of the cornea has been developed to predict the DCR parameters. This FE model has been replaced with a PCE-based surrogate model to speed up the simulation step. The uncertainties in the geometry and material model of the cornea have been propagated through the surrogate model to estimate the distributions of the DCR parameters. In the second step, the combination of DCR parameters and the input parameters provide a proper parameter space for developing an efficient data-driven PCE model to predict the IOP. Moreover, sensitivity analysis by using PCE-based Sobol indices has been performed. The results demonstrate the accuracy and efficiency of the proposed method in predicting the IOP. Sensitivity analysis revealed that IOP measurement was influenced mostly by deflection amplitude and applanation time. The analysis indicates the importance of the interactions between the parameters.
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Affiliation(s)
- Vahid Yaghoubi
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran; Structural Integrity & Composites, Faculty of Aerospace Engineering, Delft University of Technology, 2629 HS, Delft, Netherlands.
| | - Hamed Setayeshnasab
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - Peiman Mosaddegh
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - Mahmoud Kadkhodaei
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
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Yousefi A, Roberts CJ, Reilly MA. The Shape of Corneal Deformation Alters Air Puff–Induced Loading. Front Bioeng Biotechnol 2022; 10:848060. [PMID: 35433651 PMCID: PMC9006101 DOI: 10.3389/fbioe.2022.848060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/03/2022] [Indexed: 12/03/2022] Open
Abstract
Purpose: To determine the dynamic modification of the load exerted on the eye during air-puff testing by accounting for the deformation of the cornea. Methods: The effect of corneal load alteration with surface shape (CLASS) was characterized as an additional component of the load produced during the concave phase where the fluid outflow tangential to the corneal surface creates backward pressure. Concave phase duration (tCD), maximum CLASS value (CLASSmax), and the area under CLASS-time curve (CLASSint) are calculated for 26 keratoconic (KCN), 102 normal (NRL), and 29 ocular hypertensive (OHT) subjects. Tukey’s HSD tests were performed to compare the three subject groups. A p-value less than 0.05 was considered statistically significant. Results: Accounting for CLASS increased the load by 34.6% ± 7.7% at maximum concavity; these differences were greater in KCN subjects (p < 0.0001) and lower in OHT subjects (p = 0.0028) than in NRL subjects. tCD and CLASSint were significantly longer and larger, respectively, for KCN subjects than those in the NRL and OHT groups (p < 0.0001). Conclusion: Load characterization is an essential step in assessing the cornea’s biomechanical response to air-puff–induced deformation. The dynamic changes in the corneal surface shape significantly alter the load experienced by the corneal apex. This implies a subject-specific loading dynamic even if the air puff itself is identical. This is important when comparing the same eye after a surgical procedure or topical medication that alters corneal properties. Stiffer corneas are least sensitive to a change in load, while more compliant corneas show higher sensitivity.
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Affiliation(s)
- Atieh Yousefi
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, United States
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Cynthia J. Roberts
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, United States
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
- *Correspondence: Cynthia J. Roberts,
| | - Matthew A. Reilly
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, United States
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
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