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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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Baptista PML, Ferreira AS, Silva NP, Figueiredo ARM, Sampaio IC, Reis RVF, Ambrósio R, Menéres PMAM, Beirão JNM, Menéres MJFS. Scheimpflug-Based Corneal Biomechanical Analysis As A Predictor of Glaucoma in Eyes With High Myopia. Clin Ophthalmol 2024; 18:545-563. [PMID: 38410632 PMCID: PMC10895980 DOI: 10.2147/opth.s426635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/04/2024] [Indexed: 02/28/2024] Open
Abstract
Purpose To address if corneal biomechanical behavior has a predictive value for the presence of glaucomatous optical neuropathy in eyes with high myopia. Patients and Methods This observational cross-sectional study included 209 eyes from 108 consecutive patients, divided into four groups: high myopia and primary open-angle glaucoma (POAG) - HMG, n = 53; high myopia without POAG - HMNG, n = 53; non-myopic with POAG - POAG, n = 50; non-myopic and non-POAG- NMNG, n = 53. Biomechanical assessment was made through a Scheimpflug-camera-based technology. Receiver operating characteristic curves were made for the discrimination between groups. Multivariable logistic regression models were performed to address the predictive value of corneal biomechanics for the presence of glaucoma. Results Areas Under the Receiver Operating Characteristic (AUROCs) above 0.6 were found in 6 parameters applied to discriminate between HMG and HMNG and six parameters to discriminate between POAG and NMNG. The biomechanical models with the highest power of prediction for the presence of glaucoma included 5 parameters with an AUROC of 0.947 for eyes with high myopia and 6 parameters with an AUROC of 0.857 for non-myopic eyes. In the final model, including all eyes, and adjusted for the presence of high myopia, the highest power of prediction for the presence of glaucoma was achieved including eight biomechanical parameters, with an AUROC of 0.917. Conclusion Corneal biomechanics demonstrated differences in eyes with glaucoma and mainly in myopic eyes. A biomechanical model based on multivariable logistic regression analysis and adjusted for high myopia was built, with an overall probability of 91.7% for the correct prediction of glaucomatous damage.
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Affiliation(s)
- Pedro M L Baptista
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - André S Ferreira
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Faculdade de Medicina da Universidade do Porto, Universidade do Porto, Porto, Portugal
| | - Nisa P Silva
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Ana R M Figueiredo
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Isabel C Sampaio
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Rita V F Reis
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Renato Ambrósio
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, RJ, Brazil
- Department of Cornea and Refractive Surgery, Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
- Federal University of São Paulo (UNIFESP), São Paulo, Brazil
- Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro & Maceió, Brazil
| | - Pedro M A M Menéres
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - João N M Beirão
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Maria J F S Menéres
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
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Borrego-Sanz L, Morales-Fernández L, Saénz-Francés San Baldomero F, Díaz Valle D, Pato Cour E, Méndez Fernández R, García Feijóo J, Rodríguez Rodríguez L. Corneal Biomechanics in Non-infectious Uveitis Measured by Corvis ST: A Pilot Study. Ocul Immunol Inflamm 2023; 31:1765-1771. [PMID: 35980346 DOI: 10.1080/09273948.2022.2108462] [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: 12/29/2021] [Accepted: 07/26/2022] [Indexed: 10/15/2022]
Abstract
PURPOSE To assess differences between corneal biomechanical properties in patients with non-infectious uveitis and healthy subjects using CorVis. METHODS 77 patients with non-infectious uveitis and 47 control subjects were recruited. Biomechanical parameters were measured: deformation amplitude (DA), A-1 length and A-2 length (L1, L2), A-1 velocity and A-2 velocity (V1, V2), peak distance (PD) and HC radius (highest concavity radius). AUC ROC and correlation between clinical variables and biomechanical properties were determined. RESULTS Lower HC Radius and IOPb and higher DA and V1 was found in uveitis group. Statistical differences between cases using systemic medications and those with topical treatment were found in L1. Differences were showed between those cases with active and inactive uveitis in PD, DA, V2 and L2. The biomechanical parameter with the best discriminatory capacity of uveitis disease was HC Radius. CONCLUSION Differences in corneal biomechanical properties between non-infectious uveitis and healthy eyes were found.
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Affiliation(s)
- Lara Borrego-Sanz
- Ophthalmology Department, Clínico San Carlos Hospital, Madrid, Spain
| | | | | | - David Díaz Valle
- Ophthalmology Department, Clínico San Carlos Hospital, Madrid, Spain
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Pérez-Corral J, Cardona G, Piñero DP, Barroso D, Armadans L. Short- and mid-term changes in CORVIS ST parameters in successful, adult orthokeratology patients. Clin Exp Optom 2023; 106:726-733. [PMID: 36375143 DOI: 10.1080/08164622.2022.2140031] [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: 03/27/2022] [Revised: 07/12/2022] [Accepted: 10/20/2022] [Indexed: 11/16/2022] Open
Abstract
CLINICAL RELEVANCE The changes in various biomechanical and tomographic characteristics of the cornea associated with orthokeratology may allow us to identify potential mid- and long-term structural alterations, resulting in a better understanding of the governing mechanisms of this procedure and in its optimisation. BACKGROUND The study aimed at describing short and mid-term changes in CORVIS ST® parameters and indices in orthokeratology (ortho-k), and their diurnal variations. METHODS A prospective observational study was designed in which several CORVIS ST® parameters of 75 new adult participants successfully fitted with overnight ortho-k Seefree® (Conóptica - Hecht Contactlinsen) contact lenses were explored. Measurements were conducted in baseline (BL) conditions and in the morning and evening at the one-night (1 NM/1NT), one-week (1WM/1 WT) and 3-month (3 MM/3MT) follow-up visits. RESULTS Statistically significant differences were found in DARatio_2 mm, IntRad, ARTh, CBI and TBI following overnight ortho-k, when compared with BL values, with most values reaching stability at 1WM or reverting to BL values at 3 MM. The ARTh and CBI parameters showed some of the most significant temporal variations (both p < 0.001), probably reflecting the encountered differences in central corneal thickness between BL and 1WM (p = 0.010) and between BL and 3 MM (p = 0.016). In general, corneal rigidity was higher in the morning at all follow-up visits, and decreased during the day. No statistically significant changes in adjusted intraocular pressure values were found. CONCLUSION Ortho-k in adults may be considered a safe procedure in terms of short and mid-term changes in CORVIS ST® parameters. The observed alterations in most of the parameters provided by the Corvis ST® probably responded to the well-described changes in corneal pachymetry and tomography, rather than to actual alterations in corneal rigidity.
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Affiliation(s)
- Joan Pérez-Corral
- School of Optics and Optometry, Department of Optics and Optometry, Universitat Politècnica de Catalunya, Terrassa, Spain
| | - Genis Cardona
- School of Optics and Optometry, Department of Optics and Optometry, Universitat Politècnica de Catalunya, Terrassa, Spain
| | - David P Piñero
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - David Barroso
- School of Optics and Optometry, Department of Optics and Optometry, Universitat Politècnica de Catalunya, Terrassa, Spain
| | - Laura Armadans
- School of Optics and Optometry, Department of Optics and Optometry, Universitat Politècnica de Catalunya, Terrassa, Spain
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Chen X, Cao H, Huo Y, Song J, Zou H, Li J, Hou J, Wang Y. Screening of sensitive in vivo characteristics for early keratoconus diagnosis: a multicenter study. Front Bioeng Biotechnol 2023; 11:1158299. [PMID: 37600309 PMCID: PMC10436515 DOI: 10.3389/fbioe.2023.1158299] [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: 02/03/2023] [Accepted: 07/21/2023] [Indexed: 08/22/2023] Open
Abstract
Purpose: To analyze and compare sensitive in vivo characteristics for screening early keratoconus. Methods: This multicenter, case-control study included 712 eyes, after matching for age and biomechanically corrected intraocular pressure, from three clinics in different cities. The keratoconus (n = 288), early keratoconus (n = 91), and normal cornea (n = 333) groups included eyes diagnosed with bilateral keratoconus, fellow eyes with relatively normal topography with unilateral keratoconus, and normal eyes before refractive surgery, respectively. After adjusting for central corneal thickness, differences in vivo characteristics were analyzed among the three groups. The in vivo characteristics were measured by Pentacam and Corvis ST. Fifty-four indices were evaluated to screen for a sensitive index for the detection of early keratoconus. Results: Significant differences were observed in 26 of the 36 corneal biomechanical indeces between the early keratoconus and normal corneas. The area under the receiver operating characteristic curve of tomographic and biomechanical index, Belin/Ambrósio deviation, and Da in differentiating keratoconus from normal cornea was 1.000. Among the top five indeces of the area under the receiver operating characteristic curve for detecting early keratoconus, the corneal biomechanical-related index accounted for 80% (4/5), including A1 dArc length, highest concavity radius, A2 time, and tomographic and biomechanical index, of which the area under the receiver operating characteristic curve of A1 dArc length was 0.901. Conclusion: A1 dArc length and several corneal biomechanical indices are highly sensitive for the detection of early keratoconus, even in the absence of topographic abnormalities. Ophthalmologists should focus on the clinical application of corneal biomechanics and combine corneal tomography for the timely and accurate detection of early keratoconus.
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Affiliation(s)
- Xuan Chen
- School of Medicine, Nankai University, Tianjin, China
| | - Huazheng Cao
- School of Medicine, Nankai University, Tianjin, China
| | - Yan Huo
- School of Medicine, Nankai University, Tianjin, China
| | - Jiaxin Song
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Haohan Zou
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Tianjin, China
| | - Jing Li
- Shanxi Eye Hospital, Xi’an People’s Hospital, Xi’an, Shanxi, China
| | - Jie Hou
- Jinan Mingshui Eye Hospital, Jinan, Shandong, China
| | - Yan Wang
- School of Medicine, Nankai University, Tianjin, China
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Nankai University Affiliated Eye Hospital, Tianjin, China
- Nankai Eye Institute, Nankai University, Tianjin, China
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Augustin VA, Son HS, Kovalchuk B, Yildirim TM, Köppe MK, Auffarth GU, Khoramnia R. Biomechanical Analysis of Tomographically Regular Keratoconus Fellow Eyes Using Corvis ST. Klin Monbl Augenheilkd 2023; 240:944-951. [PMID: 37567232 DOI: 10.1055/a-2130-7503] [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: 08/13/2023]
Abstract
BACKGROUND Keratoconus is a bilateral, yet asymmetric disease. In rare cases, the second eye may show no signs of tomographic changes. The purpose of this study was to analyze the biomechanical characteristics in tomographically regular keratoconus fellow eyes. MATERIALS AND METHODS This retrospective, consecutive case series analyzed 916 eyes of 458 patients who presented to our keratoconus clinic between November 2020 and October 2022. Primary outcome measures included best-corrected visual acuity (BCVA), tomographic Scheimpflug analysis using Pentacam AXL (Oculus, Wetzlar, Germany), and biomechanical assessment using Corvis ST (Oculus, Wetzlar, Germany). Tomographic changes were assessed via analysis of the anterior and posterior curvature, K-max, thinnest corneal thickness (TCT), the Belin/Ambrosio Deviation Display (BAD-D), and the ABCD-Grading. Biomechanical changes were analyzed using Corvis Biomechanical Index (CBI) and Tomographic Biomechanical Index (TBI). RESULTS Of 916 eyes, 34 tomographically regular fellow eyes (7.4%) were identified and included in the analysis. Overall, the mean BCVA was - 0.02 ± 0.13 logMAR. Tomographic analysis showed mean K-max of 43.87 ± 1.21 D, mean TCT of 532 ± 23 µm, and mean BAD-D of 1.02 ± 0.43. Biomechanical analysis demonstrated mean CBI of 0.28 ± 0.26 and mean TBI of 0.34 ± 0.30. While normal CBI-values were observed in 16 (47%) of 34 eyes, only 13 eyes (38%) showed a regular TBI and only 7 eyes (21%) showed regular TBI and CBI. The sensitivity of CBI and TBI to detect a tomographically normal keratoconus fellow eye was 53% and 62%, respectively. CONCLUSION A highly asymmetric corneal ectasia with regular tomographic finding in a fellow eye is rare among keratoconus patients. In such cases, a biomechanical analysis may be useful in detecting early signs of corneal ectasia. In our analysis, the TBI showed high sensitivity for detecting a biomechanical abnormality in tomographically regular fellow eyes.
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Affiliation(s)
- Victor A Augustin
- Universitäts-Augenklinik Heidelberg, David J. Apple International Laboratory for Ocular Pathology und International Vision Correction Research Centre (IVCRC), Heidelberg, Deutschland
| | - Hyeck-Soo Son
- Universitäts-Augenklinik Heidelberg, David J. Apple International Laboratory for Ocular Pathology und International Vision Correction Research Centre (IVCRC), Heidelberg, Deutschland
| | - Bogdana Kovalchuk
- Universitäts-Augenklinik Heidelberg, David J. Apple International Laboratory for Ocular Pathology und International Vision Correction Research Centre (IVCRC), Heidelberg, Deutschland
| | - Timur Mert Yildirim
- Universitäts-Augenklinik Heidelberg, David J. Apple International Laboratory for Ocular Pathology und International Vision Correction Research Centre (IVCRC), Heidelberg, Deutschland
| | - Maximilian K Köppe
- Universitäts-Augenklinik Heidelberg, David J. Apple International Laboratory for Ocular Pathology und International Vision Correction Research Centre (IVCRC), Heidelberg, Deutschland
| | - Gerd U Auffarth
- Universitäts-Augenklinik Heidelberg, David J. Apple International Laboratory for Ocular Pathology und International Vision Correction Research Centre (IVCRC), Heidelberg, Deutschland
| | - Ramin Khoramnia
- Universitäts-Augenklinik Heidelberg, David J. Apple International Laboratory for Ocular Pathology und International Vision Correction Research Centre (IVCRC), Heidelberg, Deutschland
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Heidari H, Momeni-Moghaddam H, Jadidi K, Pirhadi S, Moshirfar M. Changes in Stress-Strain Index and Corneal Biomechanics in Granular Corneal Dystrophy. J Clin Med 2022; 11:jcm11216571. [PMID: 36362797 PMCID: PMC9657534 DOI: 10.3390/jcm11216571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 10/31/2022] [Accepted: 11/03/2022] [Indexed: 11/09/2022] Open
Abstract
Background: The aim of this study was to assess stress-strain index (SSI) and corneal biomechanical parameters in eyes with granular corneal dystrophy (GCD). Methods: This case-control study included 12 eyes of 12 patients with GCD (mean age 45.2 ± 18.7 years) and 20 eyes of 20 healthy individuals (mean age 54.4 ± 3.8 years). In addition to SSI, dynamic corneal response (DCR) parameters were assessed at the first and second applanation, including length (AL1, AL2), velocity (AV1, AV2), time (AT1, AT2), and deformation amplitude (DA A1, DA A2), and at the highest concavity (HC) phase, including DA, peak distance (PD), radius (HCR), and DA ratio (DAR 1 and 2 mm), by Corvis ST. Central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were considered covariates in comparing DCR parameters between the two groups. Results: SSI was statistically significantly lower in eyes with GCD than in normal eyes (p = 0.04). The corneal velocity towards the first applanation was 0.02 m/s faster in the GCD eyes AV1 (0.15 ± 0.02 vs. 0.13 ± 0.02 m/s, p < 0.001) and IR (7.48 ± 1.01 vs. 6.80 ± 1.22 mm, p = 0.003) parameters were significantly higher in the GDC group, while AT1 (7.33 ± 0.66 vs. 7.47 ± 0.36 ms, p = 0.002) and HCR (7.42 ± 0.76 vs. 8.20 ± 1.08 mm, p = 0.014) were significantly lower in the normal group. Conclusions: GCD led to a change in biomechanical properties of the cornea. SSI refers to fewer stiff corneas in GDC than normal.
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Affiliation(s)
- Hamidreza Heidari
- Rehabilitation Research Center, Iran University of Medical Sciences, Tehran 14496-14535, Iran
| | - Hamed Momeni-Moghaddam
- Rehabilitation Sciences Research Center, Zahedan University of Medical Sciences, Zahedan 43463-98167, Iran
- Correspondence: (H.M.-M.); (M.M.)
| | - Khosrow Jadidi
- Vision Health Research Center, Semnan University of Medical Sciences, Semnan 35147-99442, Iran
| | - Shiva Pirhadi
- Vision Health Research Center, Semnan University of Medical Sciences, Semnan 35147-99442, Iran
- Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran 14496-14535, Iran
| | - Majid Moshirfar
- Hoopes Vision Research Center, Hoopes Vision, 11820 S. State St. #200, Draper, UT 84020, USA
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- Utah Lions Eye Bank, Murray, UT 84107, USA
- Correspondence: (H.M.-M.); (M.M.)
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Augustin VA, Son HS, Baur I, Zhao L, Auffarth GU, Khoramnia R. Detecting subclinical keratoconus by biomechanical analysis in tomographically regular keratoconus fellow eyes. Eur J Ophthalmol 2021; 32:11206721211063740. [PMID: 34841930 DOI: 10.1177/11206721211063740] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
PURPOSE To analyze the tomographically non-affected second eyes of keratoconus patients using the Corvis ST to detect any biomechanical abnormalities or subclinical keratoconus. METHODS In this retrospective, single-center, consecutive case series 244 eyes of 122 keratoconus patients were analyzed between November 2020 and February 2021. Fourteen fellow eyes fulfilled the inclusion criteria and showed no clinical or tomographic signs of keratoconus. Main outcome measures included best-corrected visual acuity, tomographic and biomechanical analyses using Scheimpflug imaging: Pentacam and Corvis ST (Oculus, Wetzlar, Germany). Tomographic analyses included anterior and posterior simulated keratometry, K-Max, central corneal thickness, thinnest corneal thickness, Belin/Ambrosio Ectasia Display, and the ABCD grading system. For biomechanical analyses, the corneal biomechanical index (CBI) and tomographic biomechanical index were used. RESULTS The mean best-corrected visual acuity was 0.01 ± 0.10 logMAR. Mean K-Max was 43.79 ± 1.12 D, mean central corneal thickness 529 ± 25 µm, mean thinnest corneal thickness 524 ± 23 µm, and mean Belin/Ambrosio Ectasia Display 1.0 ± 0.32. The mean CBI was 0.30 ± 0.21. Regular CBI values were found in six of 14 patients. The mean tomographic biomechanical index was 0.47 ± 0.22 with regular values observed in only two of 14 patients. No signs of tomographic or biomechanical abnormalities were shown in only one of 14 keratoconus fellow eyes, with regular ABCD, Belin/Ambrosio Ectasia Display, CBI and tomographic biomechanical index values. CONCLUSIONS Tomographically normal fellow eyes of keratoconus patients are rare. In these cases, a biomechanical analysis of the cornea may help detect a subclinical keratoconus. The tomographic biomechanical index was the most sensitive index to verify a mild ectasia.
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Affiliation(s)
- Victor A Augustin
- David J. Apple International Laboratory for Ocular Pathology and International Vision Correction Research Centre (IVCRC), 27178Department of Ophthalmology, 9144University of Heidelberg, Heidelberg, Germany
| | - Hyeck-Soo Son
- David J. Apple International Laboratory for Ocular Pathology and International Vision Correction Research Centre (IVCRC), 27178Department of Ophthalmology, 9144University of Heidelberg, Heidelberg, Germany
| | - Isabella Baur
- David J. Apple International Laboratory for Ocular Pathology and International Vision Correction Research Centre (IVCRC), 27178Department of Ophthalmology, 9144University of Heidelberg, Heidelberg, Germany
| | - Ling Zhao
- David J. Apple International Laboratory for Ocular Pathology and International Vision Correction Research Centre (IVCRC), 27178Department of Ophthalmology, 9144University of Heidelberg, Heidelberg, Germany
| | - Gerd U Auffarth
- David J. Apple International Laboratory for Ocular Pathology and International Vision Correction Research Centre (IVCRC), 27178Department of Ophthalmology, 9144University of Heidelberg, Heidelberg, Germany
| | - Ramin Khoramnia
- David J. Apple International Laboratory for Ocular Pathology and International Vision Correction Research Centre (IVCRC), 27178Department of Ophthalmology, 9144University of Heidelberg, Heidelberg, Germany
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Karamichos D, Escandon P, Vasini B, Nicholas SE, Van L, Dang DH, Cunningham RL, Riaz KM. Anterior pituitary, sex hormones, and keratoconus: Beyond traditional targets. Prog Retin Eye Res 2021; 88:101016. [PMID: 34740824 PMCID: PMC9058044 DOI: 10.1016/j.preteyeres.2021.101016] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 12/13/2022]
Abstract
"The Diseases of the Horny-coat of The Eye", known today as keratoconus, is a progressive, multifactorial, non-inflammatory ectatic corneal disorder that is characterized by steepening (bulging) and thinning of the cornea, irregular astigmatism, myopia, and scarring that can cause devastating vision loss. The significant socioeconomic impact of the disease is immeasurable, as patients with keratoconus can have difficulties securing certain jobs or even joining the military. Despite the introduction of corneal crosslinking and improvements in scleral contact lens designs, corneal transplants remain the main surgical intervention for treating keratoconus refractory to medical therapy and visual rehabilitation. To-date, the etiology and pathogenesis of keratoconus remains unclear. Research studies have increased exponentially over the years, highlighting the clinical significance and international interest in this disease. Hormonal imbalances have been linked to keratoconus, both clinically and experimentally, with both sexes affected. However, it is unclear how (molecular/cellular signaling) or when (age/disease stage(s)) those hormones affect the keratoconic cornea. Previous studies have categorized the human cornea as an extragonadal tissue, showing modulation of the gonadotropins, specifically luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Studies herein provide new data (both in vitro and in vivo) to further delineate the role of hormones/gonadotropins in the keratoconus pathobiology, and propose the existence of a new axis named the Hypothalamic-Pituitary-Adrenal-Corneal (HPAC) axis.
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Affiliation(s)
- Dimitrios Karamichos
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA.
| | - Paulina Escandon
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Brenda Vasini
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Sarah E Nicholas
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Lyly Van
- University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA; Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Deanna H Dang
- College of Medicine, University of Oklahoma Health Sciences Center, 940 Stanton L Young, Oklahoma City, OK, USA
| | - Rebecca L Cunningham
- Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Kamran M Riaz
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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10
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Chen YY, Wang TH, Huang JY, Su CC. Relationship of axial length and corneal biomechanical properties with susceptibility to unilateral normal-tension glaucoma. Graefes Arch Clin Exp Ophthalmol 2021; 260:255-264. [PMID: 34410485 DOI: 10.1007/s00417-021-05346-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 07/04/2021] [Accepted: 07/26/2021] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Corneal biomechanics, reflecting structural vulnerabilities of the eyeball, may participate in the pathogenesis of unilateral normal-tension glaucoma. This study investigated the pathophysiology of unilateral normal-tension glaucoma using Corvis ST (OCULUS Optikgeräte GmbH) and other ocular characteristics. METHODS Eighty-three patients with normal-tension glaucoma with unilateral visual field loss and structurally unaffected fellow eyes and 111 healthy controls were included in this prospective study. Dynamic corneal response parameters, intraocular pressure measured by rebound tonometry, central corneal thickness, and axial length were assessed on the same day. Measurements were compared between affected eyes, unaffected fellow eyes, and control eyes. Risk factors for normal-tension glaucoma and unilateral involvement were the main outcome measures. RESULTS A shorter first applanation time (adjusted odds ratio, 0.061; 95% confidence interval, 0.018-0.215) and a larger peak distance (adjusted odds ratio, 4.935; 95% confidence interval, 1.547-15.739) were significant risk factors for normal-tension glaucoma and were associated with greater glaucoma severity (both P < 0.001). Axial length (adjusted odds ratio, 29.015; 95% confidence interval, 4.452-189.083) was the predominant risk factor for unilateral involvement in patients with normal-tension glaucoma. CONCLUSION The eyes with normal-tension glaucoma were more compliant than healthy eyes. Axial elongation-associated optic nerve strain may play an important role in unilateral normal-tension glaucoma with similar corneal and scleral biomechanics in both eyes.
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Affiliation(s)
- Ying-Yi Chen
- Department of Ophthalmology, National Taiwan University Hospital College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Ophthalmology, Cathay General Hospital, Taipei, Taiwan
| | - Tsing-Hong Wang
- Department of Ophthalmology, National Taiwan University Hospital College of Medicine, National Taiwan University, Taipei, Taiwan
- National Taiwan University College of Medicine, Taipei, Taiwan
| | - Jehn-Yu Huang
- Department of Ophthalmology, National Taiwan University Hospital College of Medicine, National Taiwan University, Taipei, Taiwan
- National Taiwan University College of Medicine, Taipei, Taiwan
| | - Chien-Chia Su
- Department of Ophthalmology, National Taiwan University Hospital College of Medicine, National Taiwan University, Taipei, Taiwan.
- National Taiwan University College of Medicine, Taipei, Taiwan.
- National Taiwan University Hospital, No. 7, Chung-Shan S. Rd., Taipei, Taiwan.
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11
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Xu Y, Ye Y, Chong IT, Chen Z, Xu J, Yang Y, Yu K, Lam DCC, Yu M. A Novel Indentation Assessment to Measure Corneal Biomechanical Properties in Glaucoma and Ocular Hypertension. Transl Vis Sci Technol 2021; 10:36. [PMID: 34459861 PMCID: PMC8411863 DOI: 10.1167/tvst.10.9.36] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Purpose To evaluate the ability of the new in vivo corneal indentation device (CID) to measure corneal biomechanical properties. Methods and Results In total, 186 eyes from 46 healthy subjects, 107 patients with primary open-angle glaucoma, and 33 patients with ocular hypertension were enrolled in a cross-sectional study. Measurements were performed using corneal visualization Scheimpflug technology (Corvis ST) and the CID. The deformation amplitude (DA), inward applanation time, inward applanation velocity (A1V), outward applanation time (A2T), outward applanation velocity (A2V), highest concavity time, DA ratio, max inverse radius (MIR), integrated radius, and stiffness parameter A1 were included as Corvis ST parameters, and stiffness and modulus were included as CID parameters. Associations between the Corvis ST and CID parameters and correlations between central corneal thickness and corneal biomechanical parameters were analyzed. The stiffness was significantly correlated with all the Corvis ST parameters (P < 0.05). The modulus was significantly correlated with the DA, A1V, A2T, A2V, highest concavity time, and MIR (P < 0.05). The DA, inward applanation time, A1V, A2T, A2V, DA ratio, MIR, integrated radius, and stiffness parameter A1 values and both CID-derived values were significantly correlated with central corneal thickness (P < 0.05). Conclusions Parameters derived from the CID and Corvis ST demonstrated agreement in the measurement of corneal biomechanical properties. The stiffness and modulus can characterize in vivo corneal biomechanical properties. Translational Relevance Agreeing with the Corvis ST regarding the assessment of corneal biomechanical properties, the CID can be a novel clinical tool for biomechanical evaluation of the cornea.
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Affiliation(s)
- Yunzhi Xu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yiming Ye
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Iok Tong Chong
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Zidong Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jiangang Xu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yangfan Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Keming Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - David C C Lam
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Minbin Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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12
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Baptista PM, Ambrosio R, Oliveira L, Meneres P, Beirao JM. Corneal Biomechanical Assessment with Ultra-High-Speed Scheimpflug Imaging During Non-Contact Tonometry: A Prospective Review. Clin Ophthalmol 2021; 15:1409-1423. [PMID: 33854295 PMCID: PMC8039844 DOI: 10.2147/opth.s301179] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/05/2021] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND In recent years, increasing interest has arisen in the application of data from corneal biomechanics in many areas of ophthalmology, particularly to assist in the detection of early corneal ectasia or ectasia susceptibility, to predict corneal response to surgical or therapeutic interventions and in glaucoma management. Technology has evolved and, recently, the Scheimpflug principle was associated with a non-contact air-puff tonometer, allowing a thorough analysis of corneal biomechanics and a biomechanically corrected intraocular pressure assessment, opening up new perspectives both in ophthalmology and in other medical areas. Data from corneal biomechanics assessment are being integrated in artificial intelligence models in order to increase its value in clinical practice. OBJECTIVE To review the state of the art in the field of corneal biomechanics assessment with special emphasis to the technology based on ultra-high-speed Scheimpflug imaging during non-contact tonometry. SUMMARY A meticulous literature review was performed until the present day. We used 136 published manuscripts as our references. Both information from healthy individuals and descriptions of possible associations with systemic diseases are described. Additionally, it exposed information regarding several fields of ocular pathology, from cornea and ocular surface through areas of refractive surgery and glaucoma until vascular and structural diseases of the chorioretinal unit.
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Affiliation(s)
- Pedro Manuel Baptista
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal
| | - Renato Ambrosio
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, RJ, Brazil
- Department of Cornea and Refractive Surgery, Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Department of Opthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
- Federal University of São Paulo (UNIFESP), São Paulo, Brazil
- Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro & Maceió, Brazil
| | - Luis Oliveira
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Pedro Meneres
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal
| | - Joao Melo Beirao
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal
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13
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Kang H, Qian X, Chen R, Wodnicki R, Sun Y, Li R, Li Y, Shung KK, Chen Z, Zhou Q. 2-D Ultrasonic Array-Based Optical Coherence Elastography. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:1096-1104. [PMID: 33095699 PMCID: PMC8106462 DOI: 10.1109/tuffc.2020.3033304] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Acoustic radiation force optical coherence elastography (ARF-OCE) has been successfully implemented to characterize the biomechanical properties of soft tissues, such as the cornea and the retina, with high resolution using single-element ultrasonic transducers for ARF excitation. Most currently proposed OCE techniques, such as air puff and ARF, have less capability to control the spatiotemporal information of the induced region of deformation, resulting in limited accuracy and low temporal resolution of the shear wave elasticity imaging. In this study, we propose a new method called 2-D ultrasonic array-based OCE imaging, which combines the advantages of 3-D dynamic electronic steering of the 2-D ultrasonic array and high-resolution optical coherence tomography (OCT). The 3-D steering capability of the 2-D array was first validated using a hydrophone. Then, the combined 2-D ultrasonic array OCE system was calibrated using a homogenous phantom, followed by an experiment on ex vivo rabbit corneal tissue. The results demonstrate that our newly developed 2-D ultrasonic array-based OCE system has the capability to map tissue biomechanical properties accurately, and therefore, has the potential to be a vital diagnostic tool in ophthalmology.
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14
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Baptista PM, Marta AA, Marques JH, Abreu AC, Monteiro S, Menéres P, Pinto MDC. The Role of Corneal Biomechanics in the Assessment of Ectasia Susceptibility Before Laser Vision Correction. Clin Ophthalmol 2021; 15:745-758. [PMID: 33642854 PMCID: PMC7903962 DOI: 10.2147/opth.s296744] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 01/20/2021] [Indexed: 01/02/2023] Open
Abstract
Purpose To describe the tomographic and corneal biomechanical status of a sample of eyes excluded from LVC and to present the differences in biomechanical behavior in relation to cutoffs of clinical- and tomography-based screening methods used in clinical practice. Patients and Methods Observational cross-sectional study including 61 eyes from 32 consecutive patients who were excluded from LVC in our department. Clinical and demographic data were collected from the patients’ clinical records. Tomographic data was assessed with a Scheimpflug camera (Pentacam, OCULUS®). Ablation depth (µm) and residual stromal bed (µm) were calculated by the WaveLight® EX500 laser system software (Alcon, EUA). The corneal biomechanical assessment was made through ultra-high speed Scheimpflug imaging during noncontact tonometry (Corvis ST, OCULUS®). Several ectasia risk scores were analyzed. Results Mean age was 31.0±6 years old and mean manifest spherical equivalent was −2.01 ± 2.3D. Belin–Ambrósio deviation index was the tomographic parameter with higher proportion of eyes within the ectasia high risk interval. In the biomechanical assessment, more than 95% of eyes met the criteria for ectasia susceptibility in four of the first generation and in two of the second generation parameters. In a cutoff based comparative analysis, eyes with Kmax ≥45.5 D, eyes with VCOMA <0 and eyes with ARTmax ≤350 presented significantly softer corneal biomechanical behavior. Conclusion The majority of eyes excluded from LVC in the present study met the criteria for ectasia susceptibility in several biomechanical parameters, validating the clinical and tomographic based screening prior to LVC in our center. Differences found in the biomechanical assessment regarding cutoffs used in clinical practice highlight its differential role in characterizing risk profile of these patients. Tomography should not be overlooked and the integration of all data, including treatment-related parameters, can be the future of risk ectasia screening prior LVC.
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Affiliation(s)
- Pedro Manuel Baptista
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal
| | - Ana Ambrósio Marta
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - João Heitor Marques
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Ana Carolina Abreu
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Sílvia Monteiro
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Pedro Menéres
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal
| | - Maria do Céu Pinto
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
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15
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Wang X, McAlinden C, Zhang H, Yan J, Wang D, Wei W, Mi S. Assessment of corneal biomechanics, tonometry and pachymetry with the Corvis ST in myopia. Sci Rep 2021; 11:3041. [PMID: 33542296 PMCID: PMC7862660 DOI: 10.1038/s41598-020-80915-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 12/16/2020] [Indexed: 11/09/2022] Open
Abstract
To evaluate the repeatability of Corvis ST corneal biomechanical, tonometry and pachymetry measurements, and agreement of pachymetry measures with the Pentacam HR and RTVue OCT. Three consecutive measurements of the right eye of 238 myopic subjects were acquired with the Corvis ST, Pentacam HR, and RTVue OCT. Repeatability of Corvis ST was evaluated by within-subject standard deviation [Sw] and repeatability limit [r]. The agreement of central corneal thickness (CCT) measurements were compared among the three instruments using the Bland-Altman limits of agreement. Comparisons were further stratified by CCT (Corneathin ≤ 500 µm; Corneanormal = 500-550 µm; Corneathick > 550 µm). Sw was below 1 mmHg in Corneathin, Corneanormal, and Corneathick groups for IOP and bIOP. Sw for SP-A1 were 4.880, 6.128, 7.719 mmHg/mm respectively. Sw for CBI were 0.228, 0.157, 0.076, and correspondingly Sw for TBI and SSI were 0.094 and 0.056, 0.079 and 0.053, 0.070 and 0.053. The Bland-Altman plots for CCT implied poor agreement with mean differences of 29.49 µm between Corvis and OCT, 9.33 µm between Pentacam and OCT, and 20.16 µm between Corvis and Pentacam. The Corvis ST showed good repeatability with the exception of CBI in the various CCT groups. The CCT measured by Corvis ST was not interchangeable with Pentacam HR and RTVue OCT.
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Affiliation(s)
- Xiaorui Wang
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China.,Laser Vision Center, The First Affiliated Hospital of Northwestern University, No. 30, Fenxiang Alley, Xi'an, Shaanxi, China.,Shaanxi Institute of Ophthalmology, Xi'an, China
| | - Colm McAlinden
- Department of Ophthalmology, Singleton Hospital, Swansea Bay University Health Board, Swansea, UK
| | - Hongbing Zhang
- Laser Vision Center, The First Affiliated Hospital of Northwestern University, No. 30, Fenxiang Alley, Xi'an, Shaanxi, China.,Shaanxi Institute of Ophthalmology, Xi'an, China
| | - Jie Yan
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China
| | - Dan Wang
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China
| | - Wei Wei
- Laser Vision Center, The First Affiliated Hospital of Northwestern University, No. 30, Fenxiang Alley, Xi'an, Shaanxi, China. .,Shaanxi Institute of Ophthalmology, Xi'an, China.
| | - Shengjian Mi
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China.
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16
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Salouti R, Bagheri M, Shamsi A, Zamani M. Corneal Parameters in Healthy Subjects Assessed by Corvis ST. J Ophthalmic Vis Res 2020; 15:24-31. [PMID: 32095205 PMCID: PMC7001013 DOI: 10.18502/jovr.v15i1.5936] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 02/28/2019] [Indexed: 12/19/2022] Open
Abstract
Purpose To evaluate corneal biomechanics using Corvis ST in healthy eyes from Iranian keratorefractive surgery candidates. Methods In this prospective consecutive observational case series, the intraocular pressure (IOP), central corneal thickness (CCT), and biomechanical properties of 1,304 eyes from 652 patients were evaluated using Corvis ST. Keratometric readings and manifest refraction were also recorded. Results The mean (±SD) age of participants was 28 ± 5 years, and 31.7% were male. The mean spherical equivalent refraction was –3.50 ± 1.57 diopters (D), the mean IOP was 16.8 ± 2.9 mmHg, and the mean CCT was 531 ± 31 μm for the right eye. The respective means (±SD) corneal biomechanical parameters of the right eye were as follows: first applanation time: 7.36 ± 0.39 milliseconds (ms); first applanation length: 1.82 ± 0.22 mm; velocity in: 0.12 ± 0.04 m/s; second applanation time: 20.13 ± 0.48 ms; second applanation length: 1.34 ± 0.55 mm; velocity out: –0.67 ± 0.17 m/s; total time: 16.84 ± 0.64 ms; deformation amplitude: 1.05 ± 0.10 mm; peak distance: 4.60 ± 1.01 mm; and concave radius of curvature: 7.35 ± 1.39 mm. In the linear regression analysis, IOP exhibited a statistically significant association with the first and second applanation times, total time, velocity in, peak distance, deformation amplitude, and concave radius of curvature. Conclusion Our study results can be used as a reference for the interpretation of Corvis ST parameters in healthy refractive surgery candidates in the Iranian population. Our results confirmed that IOP is a major determinant of Corvis parameters.
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Affiliation(s)
- Ramin Salouti
- Poostchi Ophthalmology Research Center, Department of Ophthalmology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.,Salouti Cornea Research Center, Salouti Eye Clinic, Shiraz, Iran
| | - Mansoureh Bagheri
- Poostchi Ophthalmology Research Center, Department of Ophthalmology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Anis Shamsi
- Poostchi Ophthalmology Research Center, Department of Ophthalmology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Zamani
- Salouti Cornea Research Center, Salouti Eye Clinic, Shiraz, Iran
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17
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Lee H, Roberts CJ, Ambrósio R, Elsheikh A, Kang DSY, Kim TI. Effect of accelerated corneal crosslinking combined with transepithelial photorefractive keratectomy on dynamic corneal response parameters and biomechanically corrected intraocular pressure measured with a dynamic Scheimpflug analyzer in healthy myopic patients. J Cataract Refract Surg 2019; 43:937-945. [PMID: 28823441 DOI: 10.1016/j.jcrs.2017.04.036] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 04/12/2017] [Accepted: 04/12/2017] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the effect of accelerated corneal crosslinking (CXL) combined with transepithelial photorefractive keratectomy (PRK) on changes in new dynamic corneal response parameters and the biomechanically corrected intraocular pressure (IOP) measured using a dynamic Scheimpflug analyzer (Corvis ST). SETTING Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, South Korea. DESIGN Retrospective case series. METHODS Medical records of eyes of healthy myopic patients having transepithelial PRK or transepithelial PRK with CXL were examined. Main outcome variables were the biomechanically corrected IOP and new dynamic corneal response parameters including the deformation amplitude ratio at 1.0 mm (DAR1) and at 2.0 mm (DAR2), stiffness at first applanation and at highest concavity, and the integrated inverse radius preoperatively and 6 months postoperatively. RESULTS The study comprised 69 eyes (69 patients); 35 had transepithelial PRK and 34, transepithelial PRK with CXL. The DAR1, DAR2, and integrated inverse radius significantly increased, while stiffness at first applanation and at highest concavity decreased postoperatively in both groups. Changes in the DAR2 and integrated inverse radius in the transepithelial PRK group were significantly larger than in the transepithelial PRK with CXL group without and with analysis of covariance with the spherical equivalent change or corneal thickness change as a covariate. No significant differences in the biomechanically corrected IOP occurred preoperatively or postoperatively in either group. CONCLUSIONS Results indicate that prophylactic CXL combined with transepithelial PRK has a role in reducing the change in corneal biomechanical properties. The dynamic Scheimpflug analyzer showed stable biomechanically corrected IOP measurements preoperatively and postoperatively.
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Affiliation(s)
- Hun Lee
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, and Eyereum Eye Clinic (Kang), Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; the Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - Cynthia J Roberts
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, and Eyereum Eye Clinic (Kang), Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; the Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - Renato Ambrósio
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, and Eyereum Eye Clinic (Kang), Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; the Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Elsheikh
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, and Eyereum Eye Clinic (Kang), Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; the Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - David Sung Yong Kang
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, and Eyereum Eye Clinic (Kang), Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; the Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - Tae-Im Kim
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, and Eyereum Eye Clinic (Kang), Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; the Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom.
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18
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Lee H, Roberts CJ, Kim TI, Ambrósio R, Elsheikh A, Yong Kang DS. Changes in biomechanically corrected intraocular pressure and dynamic corneal response parameters before and after transepithelial photorefractive keratectomy and femtosecond laser-assisted laser in situ keratomileusis. J Cataract Refract Surg 2019; 43:1495-1503. [PMID: 29335093 DOI: 10.1016/j.jcrs.2017.08.019] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 08/25/2017] [Accepted: 08/28/2017] [Indexed: 11/16/2022]
Abstract
PURPOSE To evaluate the changes in biomechanically corrected intraocular pressure (IOP) and new dynamic corneal response parameters measured by a dynamic Scheimpflug analyzer before and after transepithelial photorefractive keratectomy (PRK) and femtosecond laser-assisted laser in situ keratomileusis (LASIK). SETTING Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, South Korea. DESIGN Retrospective case series. METHODS Medical records of patients having transepithelial PRK or femtosecond-assisted LASIK were examined. The primary outcome variables were biomechanically corrected IOP and dynamic corneal response parameters, including deformation amplitude ratio 2.0 mm, stiffness parameter at first applanation, Ambrósio relational thickness through the horizontal meridian, and integrated inverse radius before the procedure and 6 months postoperatively. RESULTS Of the 129 patients (129 eyes) in the study, 65 had transepithelial PRK and 64 had femtosecond-assisted LASIK. No significant differences in biomechanically corrected IOP were noted before and after surgery. The deformation amplitude ratio 2.0 mm and integrated inverse radius increased, whereas the stiffness parameter at first applanation and the Ambrósio relational thickness through the horizontal meridian decreased after surgery (P < .001). The changes in deformation amplitude ratio 2.0 mm and integrated inverse radius were smaller in transepithelial PRK than femtosecond-assisted LASIK (P < .001). Using analysis of covariance, with refractive error change or corneal thickness change as a covariate, the changes in deformation amplitude ratio 2.0 mm and integrated inverse radius were smaller in transepithelial PRK than femtosecond-assisted LASIK (P < .001). CONCLUSIONS The dynamic Scheimpflug analyzer showed stable biomechanically corrected IOP measurement before and after surgery. The changes in dynamic corneal response parameters were smaller with transepithelial PRK than with femtosecond-assisted LASIK, indicating less of a biomechanical effect with transepithelial PRK.
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Affiliation(s)
- Hun Lee
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Eyereum Eye Clinic (Kang), Seoul, and the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - Cynthia J Roberts
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Eyereum Eye Clinic (Kang), Seoul, and the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - Tae-Im Kim
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Eyereum Eye Clinic (Kang), Seoul, and the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - Renato Ambrósio
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Eyereum Eye Clinic (Kang), Seoul, and the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Elsheikh
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Eyereum Eye Clinic (Kang), Seoul, and the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom
| | - David Sung Yong Kang
- From the Department of Ophthalmology (Lee), International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, the Eyereum Eye Clinic (Kang), Seoul, and the Institute of Vision Research (Lee, Kim), Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea; the Department of Ophthalmology & Visual Science and Department of Biomedical Engineering (Roberts), Ohio State University, Columbus, Ohio, USA; Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, Brazil; the School of Engineering (Elsheikh), University of Liverpool, Liverpool, United Kingdom.
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Serbecic N, Beutelspacher S, Markovic L, Roy AS, Shetty R. Repeatability and reproducibility of corneal biomechanical parameters derived from Corvis ST. Eur J Ophthalmol 2019; 30:1287-1294. [PMID: 31744320 DOI: 10.1177/1120672119864554] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
INTRODUCTION The aim of this study was to evaluate repeatability and reproducibility of newly calculated biomechanical parameters of the cornea, developed by our research group. METHODS One eye from each of the 23 healthy subjects was measured three times consecutively, three times at different daytimes and on three different days. The within-subject standard deviation and coefficient of variation, as well as the intraclass correlation coefficient, were calculated for every parameter in each group. RESULTS Excellent repeatability and reproducibility (coefficient of variation < 5%, intraclass correlation coefficient > 0.75) was found for corrected values measured at A1, HC, and A2 time points (2nd A2 Time, 2nd A1 Time, 2nd HC Time, 2nd HC Def Amp and 2nd A1 Def Amp). Corneal-specific stiffness parameters, which showed good repeatability and reliability, were DA_cor (coefficient of variation = 4.02%, intraclass correlation coefficient = 0.919), KcLinear (coefficient of variation = 4.03%, intraclass correlation coefficient = 0.895), areaForceCornea (coefficient of variation = 3.34%, intraclass correlation coefficient = 0.853) and E2 (coefficient of variation = 4.1%, intraclass correlation coefficient = 0.78). Overall, most parameters fell into the category of good reliability (high intraclass correlation coefficient) and poor reproducibility (low coefficient of variation), including all the parameters describing extraocular deformation (DA_ext, AEPvED, AUC EDef, areaForceExtra, Kg and μg). Comparing the coefficient of variation values for intrasession, intersession and daytime measurements, there were no indices for diurnal changes. CONCLUSION Most parameters showed good repeatability and reliability. The extraocular stiffness parameters showed poor reproducibility. KcLinear can serve as a very reliable and repeatable indicator of corneal stiffness.
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Affiliation(s)
- Nermin Serbecic
- Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
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Effect of congenital blepharoptosis on corneal biomechanical properties and changes after ptosis surgery. Eye (Lond) 2019; 34:1055-1062. [PMID: 31558826 DOI: 10.1038/s41433-019-0586-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 07/11/2019] [Accepted: 08/27/2019] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVES We studied the difference in the corneal biomechanical parameters of ptotic and fellow eyes in patients with congenital blepharoptosis. The correlations between corneal biomechanical parameters and demographic or ocular parameters, and the changes after surgery were also researched. METHODS The corneal biomechanical parameters were measured by Corvis ST tonometry. The central corneal thickness (CCT), axial length (AL) and keratometry measurements were performed with LenStar LS900, and intraocular pressure (IOP) by non-contact applanation tonometry. The parameters were evaluated for the effect of ptosis and the relationship of corneal biomechanical parameters. These examinations were repeated 6 months after blepharoptosis surgery. RESULTS Twenty-nine patients were enroled. The Corvis ST parameters (Deformation amplitude [DA], A1 times, and A1 velocity), CCT, IOP with NCT, IOP with corrected, differed significantly between ptotic and fellow eyes. CCT was significantly positively correlated with Length A1 and IOP with Corvis, and negatively correlated with IOP corrected by Corvis of the ptotic eyes. The same tendency was found in the fellow eyes. Six months after the ptosis surgery, the differences in corneal biomechanics parameters between ptotic eyes and fellow eyes were not significantly changed. CONCLUSIONS Congenital blepharoptosis causes significant corneal biomechanical changes measured by Corvis ST. The ptotic eyes had thicker and less deformable corneas. The differences in corneal biomechanics between ptotic eyes and fellow eyes were mostly related to CCT changes. Six months after surgery, these differences in corneal biomechanics did not change significantly.
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Lopes BT, Eliasy A, Ambrosio R. Artificial Intelligence in Corneal Diagnosis: Where Are we? CURRENT OPHTHALMOLOGY REPORTS 2019. [DOI: 10.1007/s40135-019-00218-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Lee H, Kang DSY, Ha BJ, Choi JY, Kim EK, Seo KY, Kim TI. Biomechanical Properties of the Cornea Using a Dynamic Scheimpflug Analyzer in Healthy Eyes. Yonsei Med J 2018; 59:1115-1122. [PMID: 30328327 PMCID: PMC6192879 DOI: 10.3349/ymj.2018.59.9.1115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 08/18/2018] [Accepted: 08/20/2018] [Indexed: 11/27/2022] Open
Abstract
PURPOSE To investigate biomechanical properties of the cornea using a dynamic Scheimpflug analyzer according to age. MATERIALS AND METHODS In this prospective, cross-sectional, observational study, participants underwent ophthalmic investigations including corneal biomechanical properties, keratometric values, intraocular pressure (IOP), and manifest refraction spherical equivalent (MRSE). We determined the relationship of biomechanical parameters and ocular/systemic variables (participant's age, MRSE, IOP, and mean keratometric values) by piecewise regression analysis, association of biomechanical parameters with variables by Spearman's correlation and stepwise multiple regression analyses, and reference intervals (RI) by the bootstrap method. RESULTS This study included 217 eyes of 118 participants (20-81 years of age). Piecewise regression analysis between Corvis-central corneal thickness (CCT) and participant's age revealed that the optimal cut-off value of age was 45 years. No clear breakpoints were detected between the corneal biomechanical parameters and MRSE, IOP, and mean keratometric values. Corneal velocity, deformation amplitude, radius, maximal concave power, Corvis-CCT, and Corvis-IOP exhibited correlations with IOP, regardless of age (all ages, 20-44 years, and over 44 years). With smaller deformation amplitude and corneal velocity as well as increased Corvis-IOP and Corvis-CCT, IOP became significantly increased. We provided the results of determination of confidence interval from RI data using bootstrap method in three separate age groups (all ages, 20-44 years, and over 44 years). CONCLUSION We demonstrated multiple corneal biomechanical parameters according to age, and reported that the corneal biomechanical parameters are influenced by IOP.
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Affiliation(s)
- Hun Lee
- Department of Ophthalmology, International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, Korea
- The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
| | | | | | | | - Eung Kweon Kim
- The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
- Corneal Dystrophy Research Institute, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Kyoung Yul Seo
- The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
| | - Tae Im Kim
- The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.
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Mercer RN, Waring GO, Roberts CJ, Jhanji V, Wang Y, Filho JS, Hemings RA, Rocha KM. Comparison of Corneal Deformation Parameters in Keratoconic and Normal Eyes Using a Non-contact Tonometer With a Dynamic Ultra-High-Speed Scheimpflug Camera. J Refract Surg 2018; 33:625-631. [PMID: 28880338 DOI: 10.3928/1081597x-20170621-03] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 05/26/2017] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate and compare biomechanical properties in normal and keratoconic eyes using a dynamic ultra-high-speed Scheimpflug camera equipped with a non-contact tonometer (Corvis ST; Oculus Optikgeräte GmbH, Wetzlar, Germany). METHODS This retrospective study evaluated 89 eyes (47 normal, 42 keratoconic) and a validation arm of 72 eyes (33 normal, 39 keratoconic) using the Corvis ST. A diagnosis of keratoconus was established by clinical findings confirmed by topography and tomography. Dynamic corneal response parameters collected by the Corvis ST (A1 velocity, deformation amplitude [DA], DA Ratio Max 1mm, and Max Inverse Radius) and a stiffness parameter at first applanation (SP-A1) were incorporated into a novel logistic regression equation (DCR index). Area under the receiver operating curve (AUC) was used to assess the sensitivity and specificity of the DCR index. RESULTS DA, DA Ratio Max 1mm, Max Inverse Radius, and SP-A1 were each found to be statistically significantly different between normal and keratoconic eyes (Mann-Whitney test [independent samples]; P = .0077, < .0001, < .0001, and < .0001, respectively; significance level: P < .05). DCR index demonstrated high sensitivity, specificity, and overall correct detection rate (92.9%, 95.7%, and 94.4%, respectively; AUC = 98.5). The sensitivity and overall correct detection rate improved when eyes with Topographical Keratoconus Classification grades (TKC) greater than 0 were reevaluated (from 92.9% to 96.6% and from 94.4% to 96.1%, respectively). CONCLUSIONS Combining multiple biomechanical parameters (A1 velocity, DA, DA Ratio Max 1mm, Max Inverse Radius, and SP-A1) into a logistic regression equation allows for high sensitivity and specificity for distinguishing keratoconic from normal eyes. [J Refract Surg. 2017;33(9):625-631.].
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Evaluation of Corneal Biomechanics After Excimer Laser Corneal Refractive Surgery in High Myopic Patients Using Dynamic Scheimpflug Technology. Eye Contact Lens 2018; 43:371-377. [PMID: 27243355 DOI: 10.1097/icl.0000000000000280] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To compare the effect of femtosecond-assisted thin flap laser-assisted in situ keratomileusis (FS-LASIK) and photorefractive keratectomy with mitomycin-C (PRK-MMC) in highly myopic patients (>7.0 D [D]) on corneal biomechanical parameters. METHODS In this prospective comparative interventional case series, 60 patients (30 patients in each group) with a manifest refractive spherical equivalent (MRSE) greater than 7.0 D were enrolled. Corvis ST parameters were measured before and at 3 and 6 months postoperatively. RESULTS Preoperatively, mean MRSE was -8.65±1.51 D in FS-LASIK and -8.04±1.70 D in PRK-MMC groups (P=0.149), and corneal thickness was 570.67±36.79 μm and 507.12±32.55 μm, respectively (P<0.001). At 6 months, both groups showed significantly higher applanation (A) 2 time and A2-velocity (P<0.05 in both), whereas intraocular pressure (IOP), corrected IOP, A1 time, A1-velocity, and radius at highest concavity were significantly reduced (P<0.05 in all). In the FS-LASIK group, there was a significant increase in deformation amplitude (DA) (P=0.001), and significant decreases in A2-length (P=0.004). Peak distance increased in the PRK-MMC group (P=0.029). At 6 months, after controlling for fellow eye correlations and preoperative corneal thickness between the two groups, decreases in IOP, A1-time, A2-length and radius, and the increase in DA was greater in FS-LASIK. CONCLUSION This study demonstrated significant changes in Corvis ST ocular biomechanical metrics after both PRK-MMC and FS-LASIK in high myopic patients, indicating the significant effect of excimer laser refractive surgery on corneal biomechanical properties. However, changes that occur with FS-LASIK are more significant than with PRK-MMC. Further randomized studies are needed to better characterize the pattern of biomechanical changes associated with each type of surgery.
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Corneal Vibrations during Intraocular Pressure Measurement with an Air-Puff Method. JOURNAL OF HEALTHCARE ENGINEERING 2018; 2018:5705749. [PMID: 29610655 PMCID: PMC5828335 DOI: 10.1155/2018/5705749] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 10/25/2017] [Accepted: 12/11/2017] [Indexed: 12/19/2022]
Abstract
Introduction The paper presents a commentary on the method of analysis of corneal vibrations occurring during eye pressure measurements with air-puff tonometers, for example, Corvis. The presented definition and measurement method allow for the analysis of image sequences of eye responses—cornea deformation. In particular, the outer corneal contour and sclera fragments are analysed, and 3D reconstruction is performed. Methods On this basis, well-known parameters such as eyeball reaction or corneal response are determined. The next steps of analysis allow for automatic and reproducible separation of four different corneal vibrations. These vibrations are associated with (1) the location of the maximum of cornea deformation; (2) the cutoff area measured in relation to the cornea in a steady state; (3) the maximum of peaks occurring between applanations; and (4) the other characteristic points of the corneal contour. Results The results obtained enable (1) automatic determination of the amplitude of vibrations; (2) determination of the frequency of vibrations; and (3) determination of the correlation between the selected types of vibrations. Conclusions These are diagnostic features that can be directly applied clinically for new and archived data.
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Jiang Y, Li Y, Yang S, Lu TC. Tuck-in Lamellar keratoplasty with an lenticule obtained by small incision lenticule extraction for treatment of Post- LASIK Ectasia. Sci Rep 2017; 7:17806. [PMID: 29259313 PMCID: PMC5736760 DOI: 10.1038/s41598-017-18201-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 12/05/2017] [Indexed: 11/15/2022] Open
Abstract
Corneal ectasia is a rare but serious post-operative complication of LASIK. Our main aim was to describe and evaluate the efficacy and safety of tuck-in lamellar keratoplasty with an lenticule obtained by SMILE for treatment of Post LASIK Ectasia. Tuck-in lamellar keratoplasty was performed on three post-LASIK cornea ectasia patients (three eyes) with central corneal thickness less than 400 µm. Each patient was monitored for at least 12 months. Our primary outcomes measured pre and post-operatively included: Anterior segment optical coherence tomography(AS-OCT), corneal topography and monitored by slit-lamp microscopy. The mean total corneal thickness preoperatively and 1 day, 1 month, 3 months and 12 months post-op were 360.00 ± 32.07 µm, 590.00 ± 10.00 µm, 536.67 ± 11.54 µm, 523.33 ± 37.85 µm, 466.67 ± 41.63 µm. The mean lenticule implanted 1 day, 1 month, 3 months and 12 months post-op were 173.33 ± 41.63 µm,136.67 ± 25.16 µm, 133.33 ± 40.41 µm, 130.00 ± 17.32 µm. There was no evidence of immune rejection or other complications. Tuck-in lamellar keratoplasty with an lenticule obtained by SMILE seems to be a safe and alternative surgical approach in the treatment of post - LASIK cornea ectasia, especially for severe cases with cornea thickness less than 400 μm.
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Affiliation(s)
- Yang Jiang
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China
| | - Ying Li
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China.
| | - Shan Yang
- Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China
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Corneal Biomechanical Properties in High Myopia Measured by Dynamic Scheimpflug Imaging Technology. Optom Vis Sci 2017; 94:1074-1080. [DOI: 10.1097/opx.0000000000001152] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Leszczynska A, Moehler K, Spoerl E, Ramm L, Herber R, Pillunat LE, Terai N. Measurement of Orbital Biomechanical Properties in Patients with Thyroid Orbitopathy Using the Dynamic Scheimpflug Analyzer (Corvis ST). Curr Eye Res 2017; 43:289-292. [PMID: 29166180 DOI: 10.1080/02713683.2017.1405044] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE To investigate orbital biomechanical properties in patients with thyroid orbitopathy and in age- and gender-matched healthy subjects using the Corvis-ST (CST, Oculus Wetzlar, Germany). METHODS The CST allows a non-contact tonometry with an ultra-high-speed Scheimpflug device to record the deformation of the cornea during an air pulse. Biomechanical response parameters (intraocular pressure (IOP), whole eye movement length (WEMl) and time (WEMt), deflection amplitude 2 mm ratio max, deflection amplitude max, stiffness parameter, and biomechanically corrected IOP were measured in 39 patients with thyroid orbitopathy (= group I) and in 33 age- and gender-matched healthy subjects (= group II) using the CST. RESULTS Mean age in group I was 54.3 ± 11.6 years and in group II 54.2 ± 12.3 years with no statistical significant difference between the groups (P = 0.98). The gender distribution between the groups was not statistically significantly different (P = 0.51). Mean central corneal thickness was 571 ± 30 µm in group I and 563 ± 36 µm in group II (P = 0.306). There were statistically significant differences (P < 0.001) between groups I and II in mean IOP (19.3 ± 4.5 vs. 14.8 ± 2.3 mmHg, mean biomechanically corrected IOP (17.1 ± 3.4 vs. 13.4 ± 2.1 mmHg), mean WEMl (207 ± 57 vs. 322 ± 50 µm), mean WEMt (20.5 ± 1.0 vs. 21.9 ± 0.7 ms), mean IOP-adjusted WEMl (213 ± 56 vs. 314 ± 62 µm), and in mean stiffness parameter (132.5 ± 29.6 vs. 107.8 ± 23.3 mmHg/mm), respectively. CONCLUSION Biomechanical parameters as measured by the CST were significantly reduced in patients with thyroid orbitopathy compared to age- and gender-matched healthy subjects, indicating a reduction in orbital compliance in thyroid orbitopathy. The parameters WEMl and WEMt might be a useful diagnostic tool to evaluate the condition of the eyeball within the orbit.
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Affiliation(s)
- Anna Leszczynska
- a Department of Ophthalmology , University Hospital Dresden , Dresden , Germany
| | - Karolin Moehler
- a Department of Ophthalmology , University Hospital Dresden , Dresden , Germany
| | - Eberhard Spoerl
- a Department of Ophthalmology , University Hospital Dresden , Dresden , Germany
| | - Lisa Ramm
- a Department of Ophthalmology , University Hospital Dresden , Dresden , Germany
| | - Robert Herber
- a Department of Ophthalmology , University Hospital Dresden , Dresden , Germany
| | - Lutz E Pillunat
- a Department of Ophthalmology , University Hospital Dresden , Dresden , Germany
| | - Naim Terai
- a Department of Ophthalmology , University Hospital Dresden , Dresden , Germany
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Jung Y, Park HYL, Yang HJ, Park CK. Characteristics of corneal biomechanical responses detected by a non-contact scheimpflug-based tonometer in eyes with glaucoma. Acta Ophthalmol 2017. [PMID: 28636261 DOI: 10.1111/aos.13466] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
PURPOSE To determine the corneal biomechanical properties in eyes with glaucoma using a non-contact Scheimpflug-based tonometer. METHODS Corneal biomechanical responses were examined using a non-contact Scheimpflug-based tonometer. The tonometer parameters of the normal control group (n = 75) were compared with those of the glaucoma group (n = 136), including an analysis of glaucoma subgroups categorized by visual field loss. RESULTS After adjusting for potential confounding factors, including the intraocular pressure (IOP), central corneal thickness (CCT), age and axial length, the deformation amplitude was smaller in the glaucoma group (1.09 ± 0.02 mm) than in the normal control group (1.12 ± 0.02 mm; p value = 0.031). The deformation amplitude and the deflection amplitude of the severe glaucoma group (1.12 ± 0.02 mm and 0.92 ± 0.01 mm) were significantly greater than that of the early glaucoma group (1.07 ± 0.01 mm and 0.88 ± 0.11 mm, p = 0.006 and p = 0.031), whereas that of the moderate glaucoma group (1.09 ± 0.02 mm and 0.90 ± 0.02 mm) was greater than that of the early glaucoma group, but this difference was not statistically significant. The deformation amplitude showed a negative correlation with the CCT in the normal control group (r = -0.235), with a weaker negative relationship observed in the early glaucoma group (r = -0.099). However, in the moderate and severe glaucoma groups, the deformation amplitude showed a positive relationship with the CCT, showing an inverse relationship. The duration and number of antiglaucomatous eyedrops used had negative correlations with the CCT in eyes with moderate and severe glaucoma. CONCLUSION Overall, the glaucoma group showed significantly less deformable corneas than did the normal controls, even after adjusting for the IOP, CCT, age and axial length. However, there were also differences according to the severity of glaucoma, where the corneal deformation amplitude was greater in the severe glaucoma group compared to the early glaucoma group. The combined effects of stiffening due to glaucoma and increased viscoelastic properties caused by the chronic use of antiglaucomatous eyedrops may have resulted in the present findings.
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Affiliation(s)
- Younhea Jung
- Department of Ophthalmology and Visual Science; College of Medicine; Seoul St. Mary's Hospital; The Catholic University of Korea; Seoul Korea
| | - Hae-Young L. Park
- Department of Ophthalmology and Visual Science; College of Medicine; Seoul St. Mary's Hospital; The Catholic University of Korea; Seoul Korea
| | - Hee Jung Yang
- Department of Ophthalmology and Visual Science; College of Medicine; Seoul St. Mary's Hospital; The Catholic University of Korea; Seoul Korea
| | - Chan Kee Park
- Department of Ophthalmology and Visual Science; College of Medicine; Seoul St. Mary's Hospital; The Catholic University of Korea; Seoul Korea
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Valdez-García JE, Hernandez-Camarena JC, Lozano-Ramírez JF, Zavala J, Loya-García D, Merayo-Lloves J. Correlation of age, corneal curvature and spherical equivalent with central corneal thickness. REVISTA MEXICANA DE OFTALMOLOGÍA 2017. [DOI: 10.1016/j.mexoft.2016.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Wei Y, Xu L, Song H. Application of Corvis ST to evaluate the effect of femtosecond laser-assisted cataract surgery on corneal biomechanics. Exp Ther Med 2017; 14:1626-1632. [PMID: 28781631 PMCID: PMC5526192 DOI: 10.3892/etm.2017.4675] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 06/08/2017] [Indexed: 11/06/2022] Open
Abstract
The aim of the present study was to evaluate the effects of femtosecond laser-assisted cataract surgery (FLACS) and phacoemulsification on corneal biomechanics using corneal visualization Scheimpflug technology. The medical records of 50 eyes from 50 patients who received phacoemulsification and intraocular lens implantation because of age-related factors between June 2014 and September 2014 were retrospectively analyzed. FLACS was used in 12 eyes (FLACS group), and conventional phacoemulsification in 38 eyes (PHACO group). The evaluation of corneal biomechanical parameters included the first/second applanation time (A-time1/A-time2), the first/second applanation length (A-length1/A-length2), corneal velocity during the first/second applanation moment (Vin/Vout), highest concavity time, highest concavity-radius (HC-radius), peak distance (PD), deformation amplitude (DA), central corneal thickness (CCT), and intraocular pressure (IOP). The differences in A-length1/A-length2, IOP, CCT, PD, and DA were significant in the PHACO group between those before, 1 week after, and 1 month after surgery. No significant differences in corneal biomechanical parameters were found between those at 1 month after surgery and before surgery. There were significant differences in IOP and CCT in the FLACS group between those before, 1 week after, and 1 month after surgery. There were no significant differences in the other corneal biomechanical parameters. No significant differences were found in corneal biomechanical parameters between those 1 month after surgery and before surgery. There were significant differences in A-length1/A-length2, CCT, PD, and DA between the two groups at 1 week after surgery. There were no significant differences in corneal biomechanical parameters between the two groups at 1 month after surgery. In conclusion, the effect of FLACS on corneal biomechanics is smaller than that of phacoemulsification. The corneal biomechanical parameters are restored to preoperative levels with the healing of the incision, and the reduction of swelling of the tissue near the incision.
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Affiliation(s)
- Yinjuan Wei
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, P.R. China
| | - Lingxiao Xu
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, P.R. China
| | - Hui Song
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, P.R. China
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Chan TC, Wang YM, Yu M, Jhanji V. Comparison of corneal dynamic parameters and tomographic measurements using Scheimpflug imaging in keratoconus. Br J Ophthalmol 2017; 102:42-47. [PMID: 28559422 DOI: 10.1136/bjophthalmol-2017-310355] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Revised: 03/28/2017] [Accepted: 04/23/2017] [Indexed: 11/04/2022]
Abstract
AIM To compare the diagnostic ability of corneal tomography and corneal dynamic response measurements in normal and keratoconus eyes. METHODS Consecutive patients with grade II-III keratoconus and age-matched normal subjects were recruited. Corneal imaging was performed using Pentacam (Oculus Optikgeräte, Wetzlar, Germany) and Corvis (Oculus Optikgeräte). A beta version of Corvis software was used with three additional parameters: maximal change of arc length, deformation amplitude (DA) ratio 1 and DA ratio 2. Diagnostic ability of both devices to differentiate normal and keratoconus eyes was evaluated using receiver-operating characteristic (ROC) curves. The areas under the ROC curve (AUC) and partial AUC (pAUC) for specificity ≥80% for each parameter of Corvis and final D value of Belin/Ambrosio Enhanced Ectasia Display (BAD) were compared. RESULTS Forty-two eyes of 42 patients (21 patients with keratoconus and 21 normal subjects) were included. Both groups were age matched (p=0.760). The ROC analysis showed that the final D value of BAD had the highest AUC (0.994) and pAUC (0.194). Maximum inverse radius had the highest AUC (0.954) but a relatively lower pAUC (0.158), while DA ratio 2 had the second highest AUC (0.946) together with the highest pAUC (0.177) among Corvis parameters. There was no significant difference between AUC and pAUC of BAD compared with those of DA ratio 1 (p≥0.162) and DA ratio 2 (p≥0.208). CONCLUSIONS The results of our study suggest that Corvis measurements have the potential to differentiate keratoconus and normal eyes. The diagnostic ability of novel parameters on Corvis was comparable to Pentacam.
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Affiliation(s)
- Tommy Cy Chan
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Yu Meng Wang
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Marco Yu
- Department of Mathematics and Statistics, Hang Seng Management College, Hong Kong, China
| | - Vishal Jhanji
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.,UPMC Eye Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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He M, Ding H, He H, Zhang C, Liu L, Zhong X. Corneal biomechanical properties in healthy children measured by corneal visualization scheimpflug technology. BMC Ophthalmol 2017; 17:70. [PMID: 28514942 PMCID: PMC5436434 DOI: 10.1186/s12886-017-0463-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 05/08/2017] [Indexed: 11/30/2022] Open
Abstract
Background The aim of this study was to evaluate corneal biomechanical properties in a population of healthy children in China using corneal visualization Scheimpflug technology (CST). Methods All children underwent complete bi-ocular examinations. CST provided intraocular pressure (IOP) and corneal biomechanical parameters, including time, velocity, length and deformation amplitude at first applanation (A1T, A1V, A1L, A1DA), at second applanation (A2T, A2V, A2L, A2DA), highest concavity time (HCT), maximum deformation amplitude (MDA), peak distance (PD), and radius of curvature (RoC). Pearson correlation analysis was used to assess the impacts of demographic factors, central corneal thickness (CCT), spherical equivalent (SE), and IOP on corneal biomechanics. Results One hundred eight subjects (32 girls and 76 boys) with the mean age of 10.80 ± 4.13 years (range 4 to18 years) were included in the final analyses. The right and left eyes were highly symmetrical in SE (p = 0.082), IOP (p = 0.235), or CCT (p = 0.210). Mean A1T of the right eyes was 7.424 ± 0.340 ms; the left eyes 7.451 ± 0.365 ms. MDA was 0.993 ± 0.102 mm in the right eyes and 0.982 ± 0.100 mm in the left eyes. Mean HCT of the right eyes was 16.675 ± 0.502 ms; the left eyes 16.735 ± 0.555 ms. All CST parameters of both eye were remarkably symmetrical with the exception of A2L (p = 0.006), A1DA (p = 0.025). The majority of CST parameters of both eyes were significantly correlated with CCT and IOP (p < 0.05). However, age, SE, and sex exert little influence on the CST measurements. Conclusions This study found interocular symmetry in corneal biomechanics in healthy children eyes. Several CST biomechanical parameters in children are modified by CCT and IOP.
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Affiliation(s)
- Miao He
- Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54S Xianlie Road, 510060, Guangzhou, China
| | - Hui Ding
- Hainan Eye Hospital, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, China
| | - Hong He
- Hainan Eye Hospital, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, China
| | - Chi Zhang
- Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54S Xianlie Road, 510060, Guangzhou, China
| | - Liangping Liu
- Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54S Xianlie Road, 510060, Guangzhou, China
| | - Xingwu Zhong
- Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54S Xianlie Road, 510060, Guangzhou, China. .,Hainan Eye Hospital, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, China.
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Corneal biomechanical metrics of healthy Chinese adults using Corvis ST. Cont Lens Anterior Eye 2017; 40:97-103. [DOI: 10.1016/j.clae.2016.12.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 11/30/2016] [Accepted: 12/06/2016] [Indexed: 11/19/2022]
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Material Properties from Air Puff Corneal Deformation by Numerical Simulations on Model Corneas. PLoS One 2016; 11:e0165669. [PMID: 27792759 PMCID: PMC5085055 DOI: 10.1371/journal.pone.0165669] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 10/14/2016] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE To validate a new method for reconstructing corneal biomechanical properties from air puff corneal deformation images using hydrogel polymer model corneas and porcine corneas. METHODS Air puff deformation imaging was performed on model eyes with artificial corneas made out of three different hydrogel materials with three different thicknesses and on porcine eyes, at constant intraocular pressure of 15 mmHg. The cornea air puff deformation was modeled using finite elements, and hyperelastic material parameters were determined through inverse modeling, minimizing the difference between the simulated and the measured central deformation amplitude and central-peripheral deformation ratio parameters. Uniaxial tensile tests were performed on the model cornea materials as well as on corneal strips, and the results were compared to stress-strain simulations assuming the reconstructed material parameters. RESULTS The measured and simulated spatial and temporal profiles of the air puff deformation tests were in good agreement (< 7% average discrepancy). The simulated stress-strain curves of the studied hydrogel corneal materials fitted well the experimental stress-strain curves from uniaxial extensiometry, particularly in the 0-0.4 range. Equivalent Young´s moduli of the reconstructed material properties from air-puff were 0.31, 0.58 and 0.48 MPa for the three polymer materials respectively which differed < 1% from those obtained from extensiometry. The simulations of the same material but different thickness resulted in similar reconstructed material properties. The air-puff reconstructed average equivalent Young´s modulus of the porcine corneas was 1.3 MPa, within 18% of that obtained from extensiometry. CONCLUSIONS Air puff corneal deformation imaging with inverse finite element modeling can retrieve material properties of model hydrogel polymer corneas and real corneas, which are in good correspondence with those obtained from uniaxial extensiometry, suggesting that this is a promising technique to retrieve quantitative corneal biomechanical properties.
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In Vivo Corneal Biomechanical Properties with Corneal Visualization Scheimpflug Technology in Chinese Population. BIOMED RESEARCH INTERNATIONAL 2016; 2016:7840284. [PMID: 27493965 PMCID: PMC4963556 DOI: 10.1155/2016/7840284] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/28/2016] [Accepted: 06/19/2016] [Indexed: 12/18/2022]
Abstract
Purpose. To determine the repeatability of recalculated corneal visualization Scheimpflug technology (CorVis ST) parameters and to study the variation of biomechanical properties and their association with demographic and ocular characteristics. Methods. A total of 783 healthy subjects were included in this study. Comprehensive ophthalmological examinations were conducted. The repeatability of the recalculated biomechanical parameters with 90 subjects was assessed by the coefficient of variation (CV) and intraclass correlation coefficient (ICC). Univariate and multivariate linear regression models were used to identify demographic and ocular factors. Results. The repeatability of the central corneal thickness (CCT), deformation amplitude (DA), and first/second applanation time (A1/A2-time) exhibited excellent repeatability (CV% ≤ 3.312% and ICC ≥ 0.929 for all measurements). The velocity in/out (Vin/out), highest concavity- (HC-) radius, peak distance (PD), and DA showed a normal distribution. Univariate linear regression showed a statistically significant correlation between Vin, Vout, DA, PD, and HC-radius and IOP, CCT, and corneal volume, respectively. Multivariate analysis showed that IOP and CCT were negatively correlated with Vin, DA, and PD, while there was a positive correlation between Vout and HC-radius. Conclusion. The ICCs of the recalculated parameters, CCT, DA, A1-time, and A2-time, exhibited excellent repeatability. IOP, CCT, and corneal volume significantly influenced the biomechanical properties of the eye.
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Tian L, Wang D, Wu Y, Meng X, Chen B, Ge M, Huang Y. Corneal biomechanical characteristics measured by the CorVis Scheimpflug technology in eyes with primary open-angle glaucoma and normal eyes. Acta Ophthalmol 2016; 94:e317-24. [PMID: 25639340 DOI: 10.1111/aos.12672] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 01/01/2015] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the biomechanical properties of the cornea using Corneal Visualization Scheimpflug Technology (CorVis ST, Oculus) in eyes with primary open-angle glaucoma (POAG) and normal control eyes. METHODS A comparative cross-sectional study that included 42 patients with POAG and 60 normal control subjects matched for intraocular pressure (IOP) and central corneal thickness (CCT). IOP was measured with a Goldmann applanation tonometer (GAT). Corneal tomography and biomechanical parameters were measured with Pentacam (Oculus) and CorVis ST, respectively. Corneal biomechanical properties were compared between groups, and the associations between corneal biomechanical parameters and ocular characteristics were evaluated. Receiver operating characteristic (ROC) curves were used to establish a cut-off value for the biomechanical parameters. RESULTS The following parameters of the CorVis ST showed a significant difference between eyes with POAG and normal eyes: first applanation velocity (Vin ), second applanation time (A-time2 ), peak distance (PD) and deformation amplitude (DA). In the univariate analysis, DA was negatively correlated with IOP in both groups. For all biomechanical parameters, the areas under the ROC curve were <0.80 and thus did not reach a good level of predictive accuracy for detecting POAG. CONCLUSION CorVis ST offers an alternative method for measuring corneal biomechanical properties. Eyes with POAG exhibit a faster Vin , longer A-time2 , lower DA and longer PD than do IOP- and CCT-matched normal control eyes. The biomechanical parameters of the CorVis ST cannot readily be used for diagnosis of POAG in the individual patient.
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Affiliation(s)
- Lei Tian
- Beijing Ophthalmology and Visual Sciences Key Laboratory; Beijing Tongren Eye Center; Beijing Tongren Hospital; Capital Medical University; Beijing China
- Department of Ophthalmology; Chinese PLA General Hospital; Beijing China
| | - Dajiang Wang
- Department of Ophthalmology; Chinese PLA General Hospital; Beijing China
| | - Ying Wu
- Department of Ophthalmology; Chinese PLA General Hospital; Beijing China
| | - Xiaoli Meng
- Department of Ophthalmology; Chinese PLA General Hospital; Beijing China
| | - Bing Chen
- Department of Ophthalmology; Chinese PLA General Hospital; Beijing China
| | - Mei Ge
- Department of Ophthalmology; Chinese PLA General Hospital; Beijing China
| | - Yifei Huang
- Department of Ophthalmology; Chinese PLA General Hospital; Beijing China
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Bao F, Geraghty B, Wang Q, Elsheikh A. Consideration of corneal biomechanics in the diagnosis and management of keratoconus: is it important? EYE AND VISION 2016; 3:18. [PMID: 27382596 PMCID: PMC4932704 DOI: 10.1186/s40662-016-0048-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 06/13/2016] [Indexed: 11/10/2022]
Abstract
Keratoconus is a bilateral, non-inflammatory, degenerative corneal disease. The occurrence and development of keratoconus is associated with corneal thinning and conical protrusion, which causes irregular astigmatism. With the disruption of the collagen organization, the cornea loses its shape and function resulting in progressive visual degradation. Currently, corneal topography is the most important tool for the diagnosis of keratoconus, which may lead to false negatives among the patient population in the subclinical phase. However, it is now hypothesised that biomechanical destabilisation of the cornea may take place ahead of the topographic evidence of keratoconus, hence possibly assisting with disease diagnosis and management. This article provides a review of the definition, diagnosis, and management strategies for keratoconus based on corneal biomechanics.
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Affiliation(s)
- FangJun Bao
- The Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou City, 325027 China ; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou City, 325027 China
| | - Brendan Geraghty
- School of Engineering, University of Liverpool, Liverpool City, L69 3GH UK
| | - QinMei Wang
- The Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou City, 325027 China ; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou City, 325027 China
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool City, L69 3GH UK ; NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London City, UK
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Matalia J, Francis M, Tejwani S, Dudeja G, Rajappa N, Sinha Roy A. Role of Age and Myopia in Simultaneous Assessment of Corneal and Extraocular Tissue Stiffness by Air-Puff Applanation. J Refract Surg 2016; 32:486-93. [DOI: 10.3928/1081597x-20160512-02] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 03/17/2016] [Indexed: 11/20/2022]
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Lanza M, Iaccarino S, Bifani M. In vivo human corneal deformation analysis with a Scheimpflug camera, a critical review. JOURNAL OF BIOPHOTONICS 2016; 9:464-477. [PMID: 26871552 DOI: 10.1002/jbio.201500233] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 12/29/2015] [Accepted: 12/30/2015] [Indexed: 06/05/2023]
Abstract
Corneal morphological analysis has greatly improved in recent years, providing physicians with new and reliable parameters to study. Moreover, today corneal functional too is a routine analysis, thanks to biomechanical evaluation allowed by an ocular response analyzer (Reichert Ophthalmic Instrument, Depew, NY, USA). Corvis ST (OCULUS Optikgeräte GmbH, Wetzlar, Germany), that relies on the ultrahigh speed Scheimpflug camera, is a new device providing corneal deformation parameters measured ny scanning the cornea response to an air puff; it is an instrument able to measure intraocular pressure too. This device could open up a whole new prospective in screening, detecting and managing corneal diseases, intraocular pressure measurement and in evaluating surgical procedures involving the cornea. This paper provides a comprehensive explanation of Corvis ST measurement principles and parameters and a literature review of scientific studies.
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Affiliation(s)
- Michele Lanza
- Dipartimento Multidisciplinare di Scienze Mediche, Chirurgiche e Odontoiatriche, Seconda Università di Napoli, Napoli, Italy.
- Centro Grandi Apparecchiature, Seconda Università di Napoli, Napoli, Italy.
| | - Stefania Iaccarino
- Centro Grandi Apparecchiature, Seconda Università di Napoli, Napoli, Italy
| | - Mario Bifani
- Dipartimento Multidisciplinare di Scienze Mediche, Chirurgiche e Odontoiatriche, Seconda Università di Napoli, Napoli, Italy
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Wang LK, Tian L, Zheng YP. Determining in vivo elasticity and viscosity with dynamic Scheimpflug imaging analysis in keratoconic and healthy eyes. JOURNAL OF BIOPHOTONICS 2016; 9:454-463. [PMID: 26755237 DOI: 10.1002/jbio.201500245] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 12/01/2015] [Accepted: 12/16/2015] [Indexed: 06/05/2023]
Abstract
The paper presents a novel analysis method of corneal elasticity and viscosity based on corneal visualization Scheimpflug technology (CorVis ST) for keratoconus diagnosis. Methods for air puff force measurement and corneal imaging boundary extraction were proposed. Corneal biomechanical properties, described as tangent stiffness coefficient (STSC ) and energy absorbed area (Aabsorbed ), were assessed using the curves of the applied air puff force with corneal displacement to form a loading-unloading cycle. Twenty-five patients with keratoconus and 34 healthy control subjects, matched for intraocular pressure (IOP), were enrolled in this prospective study. The results showed that the intraclass correlation coefficients (ICC) of the STSC and Aabsorbed were 0.941 and 0.878 in Healthy group; and were 0.891 and 0.809 in Keratoconus group, respectively. Both STSC and Aabsorbed of keratoconus patients were significantly different from that of controls (both probability value P < 0.001). ROC curve analysis showed that the area under curve for STSC was 0.918 and for Aabsorbed was 0.894, which reached a good level of predictive accuracy for detecting keratoconus. Our results demonstrated that this new analysis method could be used to characterize the biomechanical properties of corneas. (a) The air puff force of CorVis ST was measured by a custom-designed force detection system. (b) Corneal displacement was extracted from CorVis ST using a proposed imaging analysis. (c) With the utilization of the air puff force and corneal dynamic displacement, an analysis method was developed to introduce new corneal biomechanical parameters - STSC and Aabsorbed .
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Affiliation(s)
- Li-Ke Wang
- Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, 999077, China
| | - Lei Tian
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, National Engineering Research Center for Ophthalmology, Beijing, 100730, China.
| | - Yong-Ping Zheng
- Interdisciplinary Division of Biomedical Engineering, Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, 999077, China.
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Ramos I, Salomão MQ, Correia FF. Corneal Deformation Response with Dynamic Ultra-high-speed Scheimpflug Imaging for Detecting Ectatic Corneas. ACTA ACUST UNITED AC 2016. [DOI: 10.5005/jp-journals-10025-1113] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
ABSTRACT
Purpose
To test the ability of metrics derived from corneal response to noncontact tonometry (NCT) to distinguish between normal and ectatic cases.
Materials and methods
The prototype of CorVis ST (Oculus, Wetzlar, Germany) was used for assessing corneal biomechanical response using ultra-high-speed 8 mm horizontal Scheimpflug photography, taking 4,330 frames per second during NCT. Patients were stratified based on clinical data, including rotating Scheimpflug corneal tomography (Oculus Pentacam HR). Biomechanical data from one eye randomly selected of 177 patients with normal corneas (N) and from 79 patients with bilateral keratoconus (KC) were investigated. Group forme fruste keratoconus (FFKC) was composed of 20 eyes with normal topographic patterns from cases with ectasia detected in the fellow eye. Group keratoconus suspect (KCS) had 16 eyes from 16 patients with topographic patterns suspicious of KC but documented stability over 3 years and normal tomographic findings. A combination of deformation parameters using linear regression analysis (Prototype Factor 1, pF1) was created by the BrAIn (Brazilian Artificial Intelligence on Corneal Tomography and Biomechanics) study group in order to provide the best possible separation of KC and normals.
Results
Statistical significant differences were found for N × KC for several parameters, including first and second applanation times, deformation amplitude, and maximal concavity radius (Mann–Whitney, p < 0.001). However, the areas under the receiver operating characteristic curves (AUC) were lower than 0.90. The pF1 had AUC of 0.945 (IC 0.909–0.97; sensitivity = 87.3% and specificity = 89.3%). The pF1 had statistically significant differences between the ectatic (KC and FFKC) and nonectatic groups (N and KCS) (p < 0.05, Kruskall–Wallis Test with post hoc Dunn's test).
Conclusion
Corneal deformation response analysis by ultra- high-speed 8 mm horizontal Scheimpflug photography provides relevant data for distinguishing ectatic and nonectatic corneas but cannot be used independently to detect KC. This data may be integrated with corneal tomography data for enhancing sensitivity and specificity for screening ectasia.
How to cite this article
Salomão MQ, Correia FF, Ramos I, Luz A, Ambrósio R Jr. Corneal Deformation Response with Dynamic Ultra-high-speed Scheimpflug Imaging for Detecting Ectatic Corneas. Int J Kerat Ect Cor Dis 2016;5(1):1-5.
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Peña-García P, Peris-Martínez C, Abbouda A, Ruiz-Moreno JM. Detection of subclinical keratoconus through non-contact tonometry and the use of discriminant biomechanical functions. J Biomech 2015; 49:353-63. [PMID: 26777602 DOI: 10.1016/j.jbiomech.2015.12.031] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 12/09/2015] [Accepted: 12/21/2015] [Indexed: 10/22/2022]
Abstract
The purpose of the present study was to develop a discriminant function departing from the biomechanical parameters provided by a non-contact tonometer (Corvis-ST, Oculus Optikgeräte, Wetzlar, Germany) to distinguish subclinical keratoconus from normal eyes. 212 eyes (120 patients) were divided in two groups: 184 healthy eyes of 92 patients aged 32.99 ± 7.85 (21-73 years) and 28 eyes of 28 patients aged 37.79 ± 14.21 (17-75 years) with subclinical keratoconus. The main outcome measures were age, sex, intraocular pressure (IOP), corneal central thickness (CCT) and other specific biomechanical parameters provided by the tonometer. Correlations between all biomechanical parameters and the rest of variables were evaluated. The biomechanical measures were corrected in IOP and CCT (since these variable are not directly related with the corneal structure and biomechanical behavior) to warrant an accurate comparison between both types of eyes. Two discriminant functions were created from the set of corrected variables. The best discriminant function created depended on three parameters: maximum Deformation Amplitude (corrected in IOP and CCT), First Applanation time (corrected in CCT) and CCT. Statistically significant differences were found between groups for this function (p=2·10(-10); Mann-Withney test). The area under the Receiving Operating Characteristic was 0.893 ± 0.028 (95% confidence interval 0.838-0.949). Sensitivity and specificity were 85.7% and 82.07% respectively. These results show that the use of biomechanical parameters provided by non-contact tonometry, previous normalization, combined with the theory of discriminant functions is a useful tool for the detection of subclinical keratoconus.
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Affiliation(s)
- Pablo Peña-García
- Department of Ophthalmology, Castilla La Mancha University, Albacete, Spain.
| | - Cristina Peris-Martínez
- Fisabio Oftalmologia Médica (FOM), Cornea and Anterior Segment Diseases Unit, Valencia, Spain; Eye Clinic Aviñó-Peris, Valencia, Spain
| | | | - José M Ruiz-Moreno
- Department of Ophthalmology, Castilla La Mancha University, Albacete, Spain
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Asaoka R, Nakakura S, Tabuchi H, Murata H, Nakao Y, Ihara N, Rimayanti U, Aihara M, Kiuchi Y. The Relationship between Corvis ST Tonometry Measured Corneal Parameters and Intraocular Pressure, Corneal Thickness and Corneal Curvature. PLoS One 2015; 10:e0140385. [PMID: 26485129 PMCID: PMC4618943 DOI: 10.1371/journal.pone.0140385] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 09/24/2015] [Indexed: 11/25/2022] Open
Abstract
The purpose of the study was to investigate the correlation between Corneal Visualization Scheimpflug Technology (Corvis ST tonometry: CST) parameters and various other ocular parameters, including intraocular pressure (IOP) with Goldmann applanation tonometry. IOP with Goldmann applanation tonometry (IOP-G), central corneal thickness (CCT), axial length (AL), corneal curvature, and CST parameters were measured in 94 eyes of 94 normal subjects. The relationship between ten CST parameters against age, gender, IOP-G, AL, CST-determined CCT and average corneal curvature was investigated using linear modeling. In addition, the relationship between IOP-G versus CST-determined CCT, AL, and other CST parameters was also investigated using linear modeling. Linear modeling showed that the CST measurement ‘A time-1’ is dependent on IOP-G, age, AL, and average corneal curvature; ‘A length-1’ depends on age and average corneal curvature; ‘A velocity-1’ depends on IOP-G and AL; ‘A time-2’ depends on IOP-G, age, and AL; ‘A length-2’ depends on CCT; ‘A velocity-2’ depends on IOP-G, age, AL, CCT, and average corneal curvature; ‘peak distance’ depends on gender; ‘maximum deformation amplitude’ depends on IOP-G, age, and AL. In the optimal model for IOP-G, A time-1, A velocity-1, and highest concavity curvature, but not CCT, were selected as the most important explanatory variables. In conclusion, many CST parameters were not significantly related to CCT, but IOP usually was a significant predictor, suggesting that an adjustment should be made to improve their usefulness for clinical investigations. It was also suggested CST parameters were more influential for IOP-G than CCT and average corneal curvature.
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Affiliation(s)
- Ryo Asaoka
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Shunsuke Nakakura
- Department of Ophthalmology, Saneikai Tsukazaki Hospital, Himeji, Japan
| | - Hitoshi Tabuchi
- Department of Ophthalmology, Saneikai Tsukazaki Hospital, Himeji, Japan
| | - Hiroshi Murata
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Yoshitaka Nakao
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima Japan
| | - Noriko Ihara
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima Japan
| | - Ulfah Rimayanti
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima Japan; Faculty of Health Science, UIN Alauddin Makassar, Sulawesi Selatan, Indonesia
| | - Makoto Aihara
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima Japan
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Kumar M, Shetty R, Jayadev C, Dutta D, Nicolsan MD, Nagaraj S, Kumar RS. Comparison of intraocular pressure measurement with Scheimpflug-based noncontact tonometer with and without hydrogel contact lenses. Indian J Ophthalmol 2015; 63:323-6. [PMID: 26044471 PMCID: PMC4463556 DOI: 10.4103/0301-4738.158072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVES The objective was to determine the repeatability of intraocular pressure (IOP) measurements made through a soft contact lens (CL) using the Scheimpflug noncontact tonometry in healthy subjects. METHODS This prospective, randomized, single-center study included one eye of 88 subjects (40 male and 48 female). Only participants without glaucoma or any other ocular pathology were included in this study. Three consecutive IOP measurements by the Scheimpflug noncontact tonometry were performed with and without daily disposable hydrogel CLs (-0.50 DS) (Dailies-nelfilcon A, 69% water, 8.7 mm base curve, 14 mm diameter, center thickness 0.10 mm) by a single operator. To avoid any bias arising from diurnal variation, all measurements were made at a similar time of day (11 am ± 1 h). The repeatability of IOP measurements using the Scheimpflug noncontact tonometry with and without CLs was evaluated using Pearson's correlation analysis. Bland-Altman plotting was used to assess the limits of agreement between the measurements with and without CLs. RESULTS The mean (± standard deviation) IOPs with and without CL were 13.80 ± 2.70 and 13.79 ± 2.54 mm of Hg respectively. The mean difference was 0.01 ± 0.16 (95% confidence interval, +1.97 to - 2.00) mm Hg. Statistical analysis via paired t-test showed no statistical difference between the two groups with (P = 0.15). A good correlation was found for IOP measurements with and without CL (r = 0.93, P < 0.001). Good test-retest reliability was found when IOP was measured with and without CL. CONCLUSION There was no significant difference between IOP measured with and without CLs by Scheimpflug noncontact tonometry.
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Affiliation(s)
- Mukesh Kumar
- Narayana Nethralaya, Bengaluru, Karnataka, India
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Bao F, Deng M, Wang Q, Huang J, Yang J, Whitford C, Geraghty B, Yu A, Elsheikh A. Evaluation of the relationship of corneal biomechanical metrics with physical intraocular pressure and central corneal thickness in ex vivo rabbit eye globes. Exp Eye Res 2015; 137:11-7. [PMID: 26026878 DOI: 10.1016/j.exer.2015.05.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 05/14/2015] [Accepted: 05/26/2015] [Indexed: 10/23/2022]
Abstract
The relationship of corneal biomechanical metrics provided by the Ocular Response Analyzer (ORA) and Corvis ST (CVS) with physical intraocular pressure (IOPp) and central corneal thickness (CCT) was evaluated. Thirty fresh enucleated eyes of 30 rabbits were used in ex vivo whole globe inflation experiments. IOPp was measured with a pressure transducer and increased from 7.5 to 37.5 mmHg in steps of 7.5 mmHg while biomechanical data was acquired using the ORA and CVS. At least 3 examinations were performed at each pressure level, where CCT and twelve biomechanical metrics were recorded and analyzed as a function of IOPp. The biomechanical metrics included corneal hysteresis (CH) and corneal resistance factor (CRF), obtained by the ORA. They also included the applanation times (A1T, A2T), lengths (A1L, A2L) and velocities (A1V, A2V), in addition to the highest concavity time (HCT), peak distance (PD), radius (HR) and deformation amplitude (DA), obtained by the CVS. The variation of CCT and the twelve biomechanical metrics for the 30 rabbit eyes tested across the 5 pressure stages considered (inter-pressure differences) were statistically significant (P = 0.00). IOPp was highly to moderately correlated with most biomechanical metrics, especially CRF, A1T, A1V, A2V, PD and DA, while the relationships with CH, A2T, A1L and HCT were poor. IOP has important influences on most corneal biomechanical metrics provided by CVS and ORA. Two biomechanical metrics A1V and HR were influenced by CCT after correcting for the effect of IOP in most pressure stages, while the correlation with others were weak. Comparisons of research groups based on ORA and CVS with different IOPs and CCTs may lead to possible misinterpretations if both or one of which are not considered in the analysis.
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Affiliation(s)
- FangJun Bao
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - ManLi Deng
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - QinMei Wang
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - JinHai Huang
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - Jing Yang
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China
| | - Charles Whitford
- School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK
| | - Brendan Geraghty
- School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK
| | - Ayong Yu
- The Affiliated Eye Hospital of WenZhou Medical University, Wenzhou, 325027, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, Zhejiang Province, 325027, China.
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK; National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, UK
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Koprowski R. Open source software for the analysis of corneal deformation parameters on the images from the Corvis tonometer. Biomed Eng Online 2015; 14:31. [PMID: 25889898 PMCID: PMC4395894 DOI: 10.1186/s12938-015-0027-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 03/27/2015] [Indexed: 11/29/2022] Open
Abstract
Background The software supplied with the Corvis tonometer (which is designed to measure intraocular pressure with the use of the air-puff method) is limited to providing basic numerical data. These data relate to the values of the measured intraocular pressure and, for example, applanation amplitudes. However, on the basis of a sequence of images obtained from the Corvis tonometer, it is possible to obtain much more information which is not available in its original software. This will be presented in this paper. Material and method The proposed software has been tested on 1400 images from the Corvis tonometer. The number of analysed 2D images (with a resolution of 200 × 576 pixels) in a sequence is arbitrary. However, in typical cases there are 140 images. The proposed software has been written in Matlab (Version 7.11.0.584, R2010b). The methods of image analysis and processing and in particular edge detection and the fast Fourier transform have been applied. Results and discussion The software allows for fully automatic (1) acquisition of 12 new parameters previously unavailable in the original software of the Corvis tonometer. It also enables off-line (2) manual and (3) automatic browsing of images in a sequence; 3D graph visualization of: (4) the corneal deformation and (5) eyeball response; 6) change of the colour palette; (7) filtration and (8) visualization of selected measured values on individual 2D images. In addition, the proposed software enables (9) to save the obtained results for further analysis and processing. Conclusions The dedicated software described in this paper enables to obtain additional new features of corneal deformations during intraocular pressure measurement. The software can be applied in the diagnosis of corneal deformation vibrations, glaucoma diagnosis, evaluation of measurement repeatability and others. The software has no licensing restrictions and can be used both commercially and non-commercially without any limitations. Electronic supplementary material The online version of this article (doi:10.1186/s12938-015-0027-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Robert Koprowski
- Department of Biomedical Computer Systems, University of Silesia, Faculty of Computer Science and Materials Science, Institute of Computer Science, ul. Będzińska 39, Sosnowiec, 41-200, Poland.
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Koprowski R, Wilczyński S, Nowinska A, Lyssek-Boron A, Teper S, Wylegala E, Wróbel Z. Quantitative assessment of responses of the eyeball based on data from the Corvis tonometer. Comput Biol Med 2015; 58:91-100. [PMID: 25622180 DOI: 10.1016/j.compbiomed.2015.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 12/31/2014] [Accepted: 01/09/2015] [Indexed: 10/24/2022]
Abstract
BACKGROUND The "air-puff" tonometers, include the Corvis, are a type of device for measuring intraocular pressure and biomechanics parameters. The paper attempts to analyse this response and its relationship with other parameters measured in the Corvis tonometer. METHODS A number of 13,400 2D images were acquired from the Corvis device and analysed (32 healthy and 16 ill people). A new method has been proposed for the analysis of responses of the eyeball based on morphological transformations and contextual operations. RESULTS The proposed algorithm enables to determine responses of the eyeball to an air puff coming from the Corvis tonometer. Additionally, responses of the eyeball have been linked to some selected features of corneal deformation. The results include, among others: (1) distinguishability between the left and right eye with an error of 7%; (2) the correlation between the area under the curve in corneal deformation and the response of the eyeball -0.26; (3) the correlation between the highest concavity time and the maximum deformation amplitude of 0.4. All these features are obtained fully automatically and repetitively at a time of 3.8s per patient (Core i7 10GB RAM). DISCUSSION It is possible to measure additional parameters of the eye deformation which are not available in the original software of the Corvis tonometer. The use of the proposed methods of image analysis and processing provides results directly from the eye response measurement when measuring intraocular pressure.
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Affiliation(s)
- Robert Koprowski
- Department of Biomedical Computer Systems, University of Silesia, Faculty of Computer Science and Materials Science, Institute of Computer Science, ul. Będzińska 39, Sosnowiec 41-200, Poland.
| | - Sławomir Wilczyński
- Department of Basic Biomedical Science, School of Pharmacy, Medical University of Silesia in Katowice, ul, Kasztanowa 3, Sosnowiec 41-200, Poland
| | - Anna Nowinska
- Ophthalmology Clinic, Medical University of Silesia, District Railway Hospital in Katowice, Katowice, Poland
| | - Anita Lyssek-Boron
- Ophthalmology Clinic, Medical University of Silesia, District Railway Hospital in Katowice, Katowice, Poland
| | - Sławomir Teper
- Ophthalmology Clinic, Medical University of Silesia, District Railway Hospital in Katowice, Katowice, Poland
| | - Edward Wylegala
- Ophthalmology Clinic, Medical University of Silesia, District Railway Hospital in Katowice, Katowice, Poland
| | - Zygmunt Wróbel
- Department of Biomedical Computer Systems, University of Silesia, Faculty of Computer Science and Materials Science, Institute of Computer Science, ul. Będzińska 39, Sosnowiec 41-200, Poland
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