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Okon MD, Ma Y, Nguyen-Rudy BA, Roberts CJ. A New Biomechanical Deformation Response Parameter: Change in Central Corneal Thickness During Air Puff Induced Corneal Deformation. Curr Eye Res 2024; 49:798-802. [PMID: 38629736 PMCID: PMC11254558 DOI: 10.1080/02713683.2024.2338228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 03/28/2024] [Indexed: 07/18/2024]
Abstract
PURPOSE To investigate the percent change in central corneal thickness (%ΔCCT) during air-puff-induced deformation as an indicator of corneal biomechanical response. METHODS Forty ex vivo human eyes from forty donors were imaged using the CorVis ST at experimentally controlled intraocular pressure (IOP) of 10, 20, 30, and 40 mmHg, followed by uniaxial strip testing to calculate tensile modulus. The CorVis ST research software tracked the anterior and posterior cornea edges and determined the dynamic corneal response (DCR) parameters. Eyes were excluded if image quality or posterior tracking issues were present. Custom algorithms were used to calculate CCT during deformation using a ray-tracing method to correct for Scheimpflug and optical distortion within each image. Correlation and stepwise regression analyses between the shape-related DCR parameters and %ΔCCT were conducted. A mixed model analysis was performed to test the effect of IOP and the strongest significant predictors of the stepwise regression on %ΔCCT. The significance threshold was set to p < 0.05. RESULTS Thirty eyes were ultimately analyzed and CCT increased significantly from the pre-deformation state to the highest concavity state at each IOP level (p < 0.001). IOP and multiple shape DCRs were found to be significantly related to %ΔCCT (p < 0.0001). The strongest predictor of %ΔCCT was integrated inverse radius (IIR) (p < 0.0001; partial R2 = 0.4772) with no other parameter having a partial R2 value greater than 0.04. The mixed model analysis showed that IIR was the sole predictor (p = 0.0098) and IOP was no longer significant as a single predictor. However, the interaction of IIR with IOP (p = 0.0023) had a significant effect on %ΔCCT. CONCLUSION Percent change in CCT is influenced by corneal stiffness as indicated by the significant relationship with IIR. The %ΔCCT may be a potential biomarker for determining differences in corneal deformation response with corneal diseases.
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Affiliation(s)
- Monica D. Okon
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Yanhui Ma
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, USA
| | | | - Cynthia J. Roberts
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, OH, USA
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Chen J, Cao X, Chen X, Li Z, Chen X, Huang S, Xie R, Ye G, Wen Y, Zhuo Y, Wei Y, Zhu Y. Causal relationship between central corneal thickness and open-angle glaucoma: Evidence from Mendelian randomization. Exp Eye Res 2024; 246:110000. [PMID: 38992852 DOI: 10.1016/j.exer.2024.110000] [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: 01/31/2024] [Revised: 05/28/2024] [Accepted: 07/09/2024] [Indexed: 07/13/2024]
Abstract
Glaucoma is the leading cause of irreversible blindness worldwide. Previous observational studies have suggested a relationship between central corneal thickness (CCT) and glaucoma; however, the results are inconsistent. This study aimed to investigate whether CCT is associated with a risk for developing open-angle glaucoma (OAG). We employed two-sample Mendelian randomization to assess the relationship between CCT and OAG, namely, primary open-angle glaucoma (POAG) and suspected glaucoma. Genetic instruments composed of variants associated with CCT at genome-wide significance (P < 5 × 10-8) were obtained from published genome-wide association studies from Iglesias et al. for discovery and Bonnemaijer et al. for replication. Summary-level statistics for these instruments for the OAG were obtained from the FinnGen Project (Release 10). Inverse-variance-weighted regression of genetic susceptibility predicted that increased CCT was positively associated with an increased risk for POAG (odds ratio [OR], 1.005; 95% confidence interval [CI], 1.002-1.008; P = 0.001) and suspected glaucoma (OR, 1.006; 95% CI, 1.003-1.009; P < 0.001). In the replication sample of CCT, increased CCT was also positively associated with an increased risk for POAG (OR, 1.004; 95% CI, 1.000-1.008; P = 0.029) and suspected glaucoma (OR, 1.005; 95% CI, 1.001-1.008; P = 0.013). We found genetic evidence supporting a potential causal association between increased CCT and the risk of POAG and suspected glaucoma in the European population. This findings indicates the clinical significance of CCT in the diagnosis and treatment of glaucoma. Further studies are needed to elucidate the underlying mechanisms of this causal relationship.
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Affiliation(s)
- Jianqi Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Xu Cao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Xiaohong Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Zhidong Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Xuhao Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Shaofen Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Rui Xie
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Guitong Ye
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Yuwen Wen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Yehong Zhuo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Yantao Wei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China.
| | - Yingting Zhu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China.
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Li X. Changes in corneal biomechanics in patients with glaucoma: a systematic review and meta-analysis. BMC Ophthalmol 2024; 24:168. [PMID: 38622519 PMCID: PMC11017643 DOI: 10.1186/s12886-024-03443-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 04/09/2024] [Indexed: 04/17/2024] Open
Abstract
INTRODUCTION Corneal biomechanics has been implicated in a variety of ocular diseases. The purpose of this study was to evaluate the relationship between the glaucoma and corneal biomechanical properties, and exploring the value of corneal biomechanics in the diagnosis and follow-up of glaucoma diseases. METHODS We searched studies in PubMed, EMBASE, Web of Science and clinicaltrials.gov., as of October 8, 2022. Only English studies were included, without publication time limit. We also searched the reference lists of published reviews. This meta-analysis was conducted with random-effects models, we used mean difference(MD) to evaluate the outcome, and the heterogeneity was assessed with the I2 statistic. Subgroup analyses were performed under the appearance of high heterogeneity. We used 11 items to describe the characteristics of included studies, publication bias was performed through the Egger's test. The quality assessment were evaluated by Newcastle-Ottawa Scale(NOS) items. RESULTS A total of 27 eligible studies were identified for data synthesis and assessment. The result of meta-analysis showed that in the comparison of included indicators, the corneal biomechanics values of glaucoma patients were statistically lower than those of normal subjects in a similar age range. The covered indicators included central corneal thickness(CCT) (MD = -8.34, 95% CI: [-11.74, -4.94]; P < 0.001), corneal hysteresis(CH)(MD = -1.54, 95% CI: [-1.88, -1.20]; P < 0.001), corneal resistance factor(CRF)( MD = -0.82, 95% CI: [-1.21, -0.44]; P < 0.001), and intraocular pressure(IOP)( corneal-compensated intraocular pressure (IOPcc): MD = 2.45, 95% CI: [1.51, 3.38]; P < 0.001); Goldmann-correlated intraocular pressure (IOPg): MD = 1.30, 95% CI: [0.41, 2.20]; P = 0.004), they all showed statistical difference. While the value of axial length(AL) did not show statistically different(MD = 0.13, 95% CI: [-0.24, 0.50]; P = 0.48). CONCLUSION Corneal biomechanics are associated with glaucoma. The findings can be useful for the design of glaucoma screening, treatment and prognosis.
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Affiliation(s)
- Xinru Li
- Department of Ophthalmology, The First People's Hospital of Yongkang Affiliated to Hangzhou Medical College, Yongkang, 321300, Zhejiang, P. R. China.
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Del Barco O, Ávila FJ, Marcellán C, Remón L. Corneal retardation time as an ocular hypertension disease indicator. Biomed Phys Eng Express 2023; 10:015014. [PMID: 38055990 DOI: 10.1088/2057-1976/ad12fa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 12/06/2023] [Indexed: 12/08/2023]
Abstract
Objective.A detailed analysis of the corneal retardation timeτas a highly related parameter to the intraocular pressure (IOP), and its plausible role as an indicator of ocular hypertension disease.Approach.A simple theoretical expression forτis derived within the corneal viscoelastic model of Kelvin-Voigt with 3 elements. This retardation time can be easily calculated from the well-known signal and pressure amplitudes of non-contact tonometers like the Ocular Response Analyzer (ORA). Then, a population-based study was performed where 100 subjects aged from 18 to 30 were analyzed (within this group, about 10% had an elevated IOP with more than 21 mmHg).Main results.A clear relationship between the corneal retardation time and the corneal-compensated intraocular pressure (IOPcc) was found, underlying the risk for ocular hypertensive (OHT) subjects with lowerτvalues to develop hypertension illnesses (due to the inability of poorly viscoelastic corneas to absorb IOP fluctuations, resulting in probable optic nerve damage).Significance.Our results might provide an useful tool to systematically discern which OHT patients (and even those with normal IOP values) are more likely to suffer glaucoma progression and, consequently, ensure an early diagnosis.
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Affiliation(s)
- Oscar Del Barco
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo, E-30100, Murcia, Spain
| | - Francisco J Ávila
- Departamento de Física Aplicada, Universidad de Zaragoza, E-50009, Zaragoza, Spain
| | - Concepción Marcellán
- Departamento de Física Aplicada, Universidad de Zaragoza, E-50009, Zaragoza, Spain
| | - Laura Remón
- Departamento de Física Aplicada, Universidad de Zaragoza, E-50009, Zaragoza, Spain
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Elhusseiny AM, Scarcelli G, Saeedi OJ. Corneal Biomechanical Measures for Glaucoma: A Clinical Approach. Bioengineering (Basel) 2023; 10:1108. [PMID: 37892838 PMCID: PMC10604716 DOI: 10.3390/bioengineering10101108] [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: 08/08/2023] [Revised: 09/11/2023] [Accepted: 09/14/2023] [Indexed: 10/29/2023] Open
Abstract
Over the last two decades, there has been growing interest in assessing corneal biomechanics in different diseases, such as keratoconus, glaucoma, and corneal disorders. Given the interaction and structural continuity between the cornea and sclera, evaluating corneal biomechanics may give us further insights into the pathogenesis, diagnosis, progression, and management of glaucoma. Therefore, some authorities have recommended baseline evaluations of corneal biomechanics in all glaucoma and glaucoma suspects patients. Currently, two devices (Ocular Response Analyzer and Corneal Visualization Schiempflug Technology) are commercially available for evaluating corneal biomechanics; however, each device reports different parameters, and there is a weak to moderate agreement between the reported parameters. Studies are further limited by the inclusion of glaucoma subjects taking topical prostaglandin analogues, which may alter corneal biomechanics and contribute to contradicting results, lack of proper stratification of patients, and misinterpretation of the results based on factors that are confounded by intraocular pressure changes. This review aims to summarize the recent evidence on corneal biomechanics in glaucoma patients and insights for future studies to address the current limitations of the literature studying corneal biomechanics.
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Affiliation(s)
- Abdelrahman M. Elhusseiny
- Department of Ophthalmology, Harvey and Bernice Jones Eye Institute, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA;
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA;
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Osamah J. Saeedi
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA;
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Ramm L, Herber R, Lorenz G, Jasper CS, Pillunat LE, Pillunat KR. Evaluation of corneal biomechanical properties using the ocular response analyzer and the dynamic Scheimpflug-Analyzer Corvis ST in high pressure and normal pressure open-angle glaucoma patients. PLoS One 2023; 18:e0281017. [PMID: 36701409 PMCID: PMC9879466 DOI: 10.1371/journal.pone.0281017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 01/12/2023] [Indexed: 01/27/2023] Open
Abstract
PURPOSE To characterize differences in corneal biomechanics in high (HPG) and normal pressure (NPG) primary open-angle glaucoma, and its association to disease severity. METHODS Corneal biomechanical properties were measured using the Ocular Response Analyzer (ORA) and the dynamic Scheimpflug-Analyzer Corvis ST (CST). Disease severity was functionally assessed by automated perimetry (Humphrey field analyzer) and structurally with the Heidelberg Retina Tomograph. To avoid a possible falsification by intraocular pressure, central corneal thickness and age, which strongly influence ORA and CST measurements, group matching was performed. Linear mixed models and generalized estimating equations were used to consider inter-eye correlation. RESULTS Following group matching, 60 eyes of 38 HPG and 103 eyes of 60 NPG patients were included. ORA measurement revealed a higher CRF in HPG than in NPG (P < 0.001). Additionally, the CST parameter integrated radius (P < 0.001) was significantly different between HPG and NPG. The parameter SSI (P < 0.001) representing corneal stiffness was higher in HPG than in NPG. Furthermore, regression analysis revealed associations between biomechanical parameters and indicators of disease severity. In HPG, SSI correlated to RNFL thickness. In NPG, dependencies between biomechanical readings and rim area, MD, and PSD were shown. CONCLUSION Significant differences in corneal biomechanical properties were detectable between HPG and NPG patients which might indicate different pathophysiological mechanisms underlying in both entities. Moreover, biomechanical parameters correlated to functional and structural indices of diseases severity. A reduced corneal deformation measured by dynamic methods was associated to advanced glaucomatous damage.
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Affiliation(s)
- Lisa Ramm
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Robert Herber
- Faculty of Medicine Carl Gustav Carus, Department of Ophthalmology, TU Dresden, Dresden, Germany
- * E-mail:
| | - Georg Lorenz
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Carolin S. Jasper
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Lutz E. Pillunat
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Karin R. Pillunat
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
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Lotfy A, Mattout HK, Fouda SM, Hemeda S. Correlation between radial peripapillary vascular density and reduced central corneal thickness in glaucoma suspect patients. BMC Ophthalmol 2022; 22:414. [PMID: 36316681 PMCID: PMC9620628 DOI: 10.1186/s12886-022-02628-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 09/29/2022] [Accepted: 10/04/2022] [Indexed: 11/27/2022] Open
Abstract
Background Optical coherence tomography (OCT) angiography (OCTA) provides a quantitative assessment of the microcirculation of the retina and choroid. It may precede the retinal nerve layer (RNFL) and optic disc head defects. Retinal nerve fiber layer defects and reduced central corneal thickness (CCT) are important parameters in the assessment of a glaucoma suspect patients. The aim of this study is to investigate any possible relationship between the reduced central corneal thickness and the radial peripapillary capillary (RPC) density defect in glaucoma suspect. Methods In this cross sectional study, 92 eyes were incorporated. Peripapillary OCT angiography (4.5 mm) and Anterior segment OCT for corneal pachymetry were done. C/D Ratio, thickness of nerve fiber layer, the blood flow indices and central corneal thickness also were evaluated. Results In eyes of glaucoma suspect patients; a significant positive correlation between CCT and total RPC density was detected (r = 0.38, P < 0.001). A strong positive correlation was also found between total RPC and peripapillary RNFL thickness (r = 0.55, P < 0.001). Conclusion Reduced central corneal thickness and peripapillary capillary density are two screening parameters for glaucoma suspect patients. The radial peripapillary capillary density is a valid diagnostic tool for glaucoma. Supplementary Information The online version contains supplementary material available at 10.1186/s12886-022-02628-z.
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Affiliation(s)
- Ayman Lotfy
- grid.31451.320000 0001 2158 2757Zagazig University, Zagazig, Egypt
| | | | | | - Sahar Hemeda
- grid.31451.320000 0001 2158 2757Zagazig University, Zagazig, Egypt
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Xu Y, Ye Y, Chen Z, Xu J, Yang Y, Fan Y, Liu P, Chong IT, Yu K, Lam DC, Yu M. Corneal Stiffness and Modulus of Normal-Tension Glaucoma in Chinese. Am J Ophthalmol 2022; 242:131-138. [DOI: 10.1016/j.ajo.2022.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 06/19/2022] [Accepted: 06/20/2022] [Indexed: 11/01/2022]
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Jóźwik A, Przeździecka-Dołyk J, Wałek E, Czerniak M, Asejczyk M. Corneal Behavior during Tonometer Measurement during the Water Drinking Test in Eyes with XEN GelStent in Comparison to Non-Implanted Eyes. J Clin Med 2022; 11:jcm11112962. [PMID: 35683350 PMCID: PMC9181234 DOI: 10.3390/jcm11112962] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 05/15/2022] [Accepted: 05/18/2022] [Indexed: 11/16/2022] Open
Abstract
Biomechanics of the cornea have significant influences on the non-contact measurement of the intraocular pressure. The corneal behaviour during tonometry is a fundamental factor in estimating its value. The aim of the study was to analyse the behaviour of the cornea during tonometric measurement with the forced change in intraocular pressure during the water drinking test. Ocular Response Analyser (Reichert) was used to the measurement. Besides four basic parameters connected with intraocular pressure (IOPg, IOPcc) and biomechanics (corneal hysteresis CH and corneal resistance factor (CRF), other parameters representing the behaviour of the cornea during a puff of air were analysed. There were 47 eyes included in the study, including 27 eyes with a XEN GelStent implanted and 20 without it. The eyes of people with monocular implementation were the reference group. The values of analysed parameters were compared before and after 10, 25, 40, and 55 min after drinking the water. The intraocular pressure increased by 2.4 mmHg (p < 0.05) for eyes with a XEN stent and 2.2 mmHg for eyes without a stent (p < 0.05) in the tenth minute after drinking of water. This change caused a decreasing of corneal hysteresis (p < 0.05) without significant changes in the corneal resistance factor (p > 0.05). Corneal hysteresis changed similarly in the reference group and the group with a XEN GelStent. The analysis of additional parameters showed a difference in the behaviour of the cornea in eyes with a XEN GelStent in comparison to the corneas of eyes without a stent. This was particularly visible in the analysis of the cornea’s behaviour during the second applanation, when the cornea returns to its baseline state after deformation caused by air puff tonometry.
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Affiliation(s)
- Agnieszka Jóźwik
- Department of Optics and Photonics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland; (A.J.); (M.C.); (M.A.)
| | - Joanna Przeździecka-Dołyk
- Department of Optics and Photonics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland; (A.J.); (M.C.); (M.A.)
- Department of Ophthalmology, Wroclaw Medical University, Borowska 213, 50-556 Wrocław, Poland;
- Correspondence:
| | - Ewa Wałek
- Department of Ophthalmology, Wroclaw Medical University, Borowska 213, 50-556 Wrocław, Poland;
| | - Magdalena Czerniak
- Department of Optics and Photonics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland; (A.J.); (M.C.); (M.A.)
| | - Magdalena Asejczyk
- Department of Optics and Photonics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland; (A.J.); (M.C.); (M.A.)
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Corneal Hysteresis, Intraocular Pressure, and Progression of Glaucoma: Time for a “Hyst-Oric” Change in Clinical Practice? J Clin Med 2022; 11:jcm11102895. [PMID: 35629021 PMCID: PMC9148097 DOI: 10.3390/jcm11102895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 05/14/2022] [Accepted: 05/15/2022] [Indexed: 12/04/2022] Open
Abstract
It is known that as people age their tissues become less compliant and the ocular structures are no different. Corneal Hysteresis (CH) is a surrogate marker for ocular compliance. Low hysteresis values are associated with optic nerve damage and visual field loss, the structural and functional components of glaucomatous optic neuropathy. Presently, a range of parameters are measured to monitor and stratify glaucoma, including intraocular pressure (IOP), central corneal thickness (CCT), optical coherence tomography (OCT) scans of the retinal nerve fibre layer (RNFL) and the ganglion cell layer (GCL), and subjective measurement such as visual fields. The purpose of this review is to summarise the current evidence that CH values area risk factor for the development of glaucoma and are a marker for its progression. The authors will explain what precisely CH is, how it can be measured, and the influence that medication and surgery can have on its value. CH is likely to play an integral role in glaucoma care and could potentially be incorporated synergistically with IOP, CCT, and visual field testing to establish risk stratification modelling and progression algorithms in glaucoma management in the future.
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Brazuna R, Salomão M, Esporcatte B, Macedo M, Esporcatte L, Colombini GNUI, Ambrósio R. Corneal biomechanics and glaucoma beyond the bidirectional impact of intraocular pressure and corneal deformation response. REVISTA BRASILEIRA DE OFTALMOLOGIA 2022. [DOI: 10.37039/1982.8551.20220036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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12
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Glaucoma – risk factors and current challenges in the diagnosis of a leading cause of visual impairment. Maturitas 2022; 163:15-22. [DOI: 10.1016/j.maturitas.2022.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/01/2022] [Accepted: 05/09/2022] [Indexed: 11/21/2022]
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Thinner Central Corneal Thickness is Associated with a Decreased Parapapillary Vessel Density in Normal Tension Glaucoma. J Ophthalmol 2022; 2022:1937431. [PMID: 35378886 PMCID: PMC8976629 DOI: 10.1155/2022/1937431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 11/18/2022] Open
Abstract
This retrospective cross-sectional study, which enrolled 124 normal tension glaucoma (NTG) eyes and 68 healthy eyes as the control, determined the association between central corneal thickness (CCT) and ocular parameters in NTG. CCT was measured using the Pentacam® system, optical coherence tomography angiography (OCT-A) was adopted to measure the peripapillary and macular area VDs, and spatial data were based on the Garway–Heath map as illustrated in OCT-A. Univariate and multivariate linear regressions were used to statistically analyze for associations between CCT and other factors. In this study, the mean age was similar for both the NTG and control groups. The mean CCT of the NTG group was significantly thinner than that of the control group (533.97 ± 33.11 µm vs. 546.78 ± 38.21 µm;
= .022). Considering all the factors, CCT negatively correlated with visual field (VF) pattern standard deviation (univariate,
= .045). To analyze structural and functional factors separately, we found a significant positive correlation between CCT and whole disc radial peripapillary capillary VD (VDRPC; multivariate,
= .019). To analyze the relationship between all factors and sectoral changes in VDRPC, a significant positive correlation was observed between CCT and inferior temporal VDRPC (univariate,
= .039) and inferior nasal VDRPC (VDRPC IN; univariate,
= .048). In conclusion, this novel study shows that among NTG participants, a thinner cornea correlated with weaker biomechanical properties susceptible to optic nerve tissue displacement, especially in response to mild transient elevation of IOP, leads to compromised ocular microcirculation.
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Prokosch V, Zwingelberg SB, Mercieca K. [Normal Tension Glaucoma]. Klin Monbl Augenheilkd 2022. [PMID: 35253131 DOI: 10.1055/a-1758-3486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Normal tension glaucoma (NTG) is a subvariant of primary open angle glaucoma (POAG) or a separate entity. NTG is defined as chronic open angle glaucoma without elevated intraocular pressure or normal intraocular pressure. Normal intraocular pressure is between 10 and 21 mmHg and is defined as two times the standard deviation of the mean intraocular pressure in the normal population. In addition to the absence of elevated intraocular pressure, all the classic symptoms of glaucoma are otherwise present. These include a conspicuous glaucomatous optic disc excavation, nerve fibre bundle defects, and corresponding visual field defects. Papillary rim haemorrhages are frequently found. The visual field defects in NDG are usually more central compared to POAG and are therefore described as more disturbing by the patient. The anterior chamber angle is open and there are no other changes suggestive of secondary glaucoma (pigment dispersion, pseudo-exfoliation). The exact pathophysiology of NDG is not well understood. Pathophysiologically, circulatory disturbances in the sense of arterial hypo- as well as hypertension may play an essential role or at least increase the susceptibility of the optic nerve to intraocular pressure fluctuations as well as blood pressure dips. Therefore, this requires not only a purely ophthalmologic but also interdisciplinary treatment of the patient with confirmed NDG. The primary goal of treatment is the reduction of intraocular pressure, which can stop the disease. This article gives an overview of epidemiology, aetiology, clinical findings and therapies.
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Prokosch V, Zwingelberg SB, Mercieca K. Normaldruckglaukome. AUGENHEILKUNDE UP2DATE 2022. [DOI: 10.1055/a-1262-3134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
ZusammenfassungDas Normaldruckglaukom wird definiert wird als primär chronisches Offenwinkelglaukom, bei dem kein erhöhter Augeninnendruck vorliegt. Trotz normalem Augeninnendruck ist das primäre Ziel der
Behandlung die Augeninnendrucksenkung, mit der es gelingen kann, die Erkrankung aufzuhalten. Dieser Artikel soll eine Übersicht über Epidemiologie, Ätiologie, Pathogenese, klinische Befunde
sowie Therapien geben.
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Díaz-Barreda MD, Sánchez-Marín I, Boned-Murillo A, Pérez-Navarro I, Martínez J, Pardina-Claver E, Pérez D, Ascaso FJ, Ibáñez J. Modification of Corneal Biomechanics and Intraocular Pressure Following Non-Penetrating Deep Sclerectomy. J Clin Med 2022; 11:jcm11051216. [PMID: 35268307 PMCID: PMC8911357 DOI: 10.3390/jcm11051216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/16/2022] [Accepted: 02/21/2022] [Indexed: 12/18/2022] Open
Abstract
Changes in the cornea can influence outcomes in patients with primary open-angle glaucoma (POAG). We aimed to evaluate the relevance of changes in corneal biomechanics and intraocular pressure (IOP) in patients undergoing non-penetrating deep sclerectomy (NPDS) with the Esnoper V2000 implant® (AJL Ophthalmic S.A., Gasteiz, Spain). We included 42 eyes of 42 patients with POAG scheduled for NPDS with the Esnoper V2000 implant. Biomechanical properties were measured by Ocular Response Analyzer® G3 (ORA; Reichert Inc., Depew, NY, USA). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) were measured the day before surgery and on day 1, 7, and 30 and 2 and 3 months after surgery. CH initially increased, fell below the presurgical value at 30 days after the surgery, and increased again at 2 and 3 months. CRF, IOPcc, and IOPg decreased on the first day after surgery, then followed a trend of increasing but stayed below pre-surgery levels. All values reached statistical significance. While observed changes in corneal biomechanics after NPDS and Esnoper V2000 implant were significant, more studies are needed if we are to understand their influence on corneal biomechanics and their clinical relevance in POAG.
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Affiliation(s)
- María Dolores Díaz-Barreda
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
- Correspondence: (M.D.D.-B.); (F.J.A.); Tel.: +34-629-863-827 (M.D.D.-B.); +34-686-574-389 (F.J.A.)
| | - Ignacio Sánchez-Marín
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
| | - Ana Boned-Murillo
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
| | - Itziar Pérez-Navarro
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
| | - Juana Martínez
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
| | - Elena Pardina-Claver
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
| | - Diana Pérez
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
| | - Francisco Javier Ascaso
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
- Correspondence: (M.D.D.-B.); (F.J.A.); Tel.: +34-629-863-827 (M.D.D.-B.); +34-686-574-389 (F.J.A.)
| | - Juan Ibáñez
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
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Rojananuangnit K. Corneal Hysteresis in Thais and Variation of Corneal Hysteresis in Glaucoma. CLINICAL OPTOMETRY 2021; 13:287-299. [PMID: 34629920 PMCID: PMC8493478 DOI: 10.2147/opto.s324187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
PURPOSE To collect the normal value data of corneal hysteresis in Thais and study the variation of corneal hysteresis in glaucomatous eyes. METHODS Retrospective cross-sectional study of corneal hysteresis (CH) in healthy non-glaucomatous and glaucomatous eyes. Demographic data, type and staging of glaucoma, Goldmann applanation tonometry (GAT) and ocular response analyzer parameters; CH, corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg) were collected. RESULTS Data from one eye of 465 normal participants were included for the normal value data of CH. Mean CH, IOPcc and IOPg were 10.18 ± 1.48, 15.01 ± 3.04 and 14.16 ± 3.06 mmHg, respectively. Average age was 57.21 ± 14.4 years. CH at the fifth percentile was 8.0 mmHg. Women had significantly higher CH than men (10.29 ± 1.46 vs 9.90 ± 1.49 mmHg, p=0.009). Moderate negative correlation was found between age and CH, r = -0.338, p<0.001. There were 695 glaucomatous eyes from 429 patients including primary-open angle glaucoma (POAG), primary close-angle glaucoma (PACG), normal tension glaucoma (NTG) and ocular hypertension (OHT). CH in each glaucoma type and severity stage (early, moderate and severe) were as follows: POAG: 8.74 ± 1.52 mmHg (9.22 ± 1.47, 8.74 ± 1.23 and 7.92 ± 1.40 mmHg, p<0.001), PACG: 9.09 ± 1.72 mmHg (9.85 ± 1.45, 9.04 ± 1.68 and 8.45 ± 1.74 mmHg, p= 0.004), NTG: 9.55 ± 1.67 mmHg (9.47 ± 1.38, 9.75 ± 2.42 and 9.77 ± 1.34 mmHg, p 0.525) and OHT: 10.10 ± 1.40 mmHg. CONCLUSION Compared with normal value data of corneal hysteresis, CH in glaucomatous eyes was lower. The more advanced glaucoma stage was associated with lower CH. Arising from normal value data, a low percentile of CH could be applied as the deviation value from normal and this dynamic property of CH could represent a glaucoma predictor in an effort to improve glaucoma care.
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Affiliation(s)
- Kulawan Rojananuangnit
- Glaucoma Unit, Ophthalmology Department, Mettapracharak (Wat Rai Khing) Hospital, Nakhon Pathom, Thailand
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Lee R, Chang RT, Wong IYH, Lai JSM, Lee JWY, Singh K. Assessment of corneal biomechanical parameters in myopes and emmetropes using the Corvis ST. Clin Exp Optom 2021; 99:157-62. [DOI: 10.1111/cxo.12341] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 08/04/2015] [Accepted: 08/06/2015] [Indexed: 11/27/2022] Open
Affiliation(s)
- Rachel Lee
- Stanford University School of Medicine, Palo Alto, California, USA,
| | - Robert T Chang
- Stanford University School of Medicine, Palo Alto, California, USA,
| | - Ian Y H Wong
- The Department of Ophthalmology, The University of Hong Kong Faculty of Medicine, Hong Kong, China,
| | - Jimmy S M Lai
- The Department of Ophthalmology, The University of Hong Kong Faculty of Medicine, Hong Kong, China,
| | - Jacky W Y Lee
- The Department of Ophthalmology, The University of Hong Kong Faculty of Medicine, Hong Kong, China,
| | - Kuldev Singh
- Stanford University School of Medicine, Palo Alto, California, USA,
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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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Caride SG, González LP, Francés FS, Feijoo JG. Study of corneal biomechanical properties in patients with childhood glaucoma. Int J Ophthalmol 2020; 13:1922-1927. [PMID: 33344191 DOI: 10.18240/ijo.2020.12.12] [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: 12/03/2019] [Accepted: 07/15/2020] [Indexed: 11/23/2022] Open
Abstract
AIM To study of corneal biomechanical properties and intraocular pressure (IOP) measured with Corvis Scheimpflug Technology (ST) in patients with childhood glaucoma (CG). METHODS Cross-sectional study in which 89 eyes were included 56 of them with CG. Only one eye per patient was included. The following variables were obtained from the clinical history and the ophthalmological examination: age, sex, IOP, number of surgeries, and the cup/disc ratio (CDR). The following parameters were recorded using Corvis ST: corrected by biomechanics IOP (bIOP), not corrected IOP (nctIOP), central corneal thickness (CCT), maximum concavity [radius, peak distance (PD) and deformation amplitude], applanation 1 and 2 (length and velocity). The mean age was 23±14.55 and 33±19.5 years old for the control group and CG group, respectively. Totally 36 were males and 53 were females. In the CG group, 7 patients were controlled only with medical treatment. Sixteen had at least one previous goniotomy, 19 had at least one trabeculectomy, and 11 had an Ahmed implant. RESULTS A significant and positive intraclass correlation coefficient was found between Goldman IOP and the IOP measured by Corvis in both groups. No differences were found between the IOP measured with Corvis and Goldman using a student t-test. Regarding biomechanical parameters, there were differences in the applanation length 2 (A-L2), in the applanation velocity 2 (A-V2) and in the PD. By sex, only the applanation length 1 (A-L1) was found to be different in control group. A positive and significant Pearson correlation was found between CDR and the A-L1. CONCLUSION Corneal biomechanical properties have shown differences between CG and healthy subjects and also between men and women.
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Affiliation(s)
- Sara Garcia Caride
- Ophthalmology, Clinico San Carlos Hospital, Profesor Martín Lagos Street, Madrid, ES 28040, Spain
| | - Lucia Perucho González
- Ophthalmology, Clinico San Carlos Hospital, Profesor Martín Lagos Street, Madrid, ES 28040, Spain
| | - Federico Sáenz Francés
- Ophthalmology, Clinico San Carlos Hospital, Profesor Martín Lagos Street, Madrid, ES 28040, Spain
| | - Julián García Feijoo
- Ophthalmology, Clinico San Carlos Hospital, Profesor Martín Lagos Street, Madrid, ES 28040, Spain
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Miki A, Yasukura Y, Weinreb RN, Maeda N, Yamada T, Koh S, Asai T, Ikuno Y, Nishida K. Dynamic Scheimpflug Ocular Biomechanical Parameters in Untreated Primary Open Angle Glaucoma Eyes. Invest Ophthalmol Vis Sci 2020; 61:19. [PMID: 32298437 PMCID: PMC7401753 DOI: 10.1167/iovs.61.4.19] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Purpose To characterize the corneal biomechanical properties of glaucoma eyes by comparing the dynamic Scheimpflug biomechanical parameters between untreated glaucoma and control eyes. Methods Cross-sectional observational data of dynamic Scheimpflug analyzer (Corvis ST) examinations were retrospectively collected from 35 eyes of 35 consecutive patients with untreated normal tension glaucoma and 35 eyes of 35 healthy patients matched on age and IOP. Ten biomechanical parameters were compared between the two groups using multivariable models adjusting for IOP, central corneal thickness, age, and axial length. The Benjamini-Hochberg method was used to correct for multiple comparison. Results In multivariable models, glaucoma was associated with smaller applanation 1 time (P < 0.001, coefficient = −0.5865), applanation 2 time (P = 0.012, coefficient = −0.1702), radius (P = 0.006, coefficient = −0.5447), larger peak distance (P = 0.011, coefficient = 0.1023), deformation amplitude ratio at 1 mm (P < 0.001, coefficient = 0.072), and integrated radius (P < 0.001, coefficient = 1.094). These associations consistently indicate greater compliance of the cornea in glaucoma eyes. Conclusions Untreated normal tension glaucoma eyes were more compliant than healthy eyes. The greater compliance (smaller stiffness) of normal tension glaucoma eyes may increase the risk of optic nerve damage. These results suggest the relevance of measuring biomechanical properties of glaucoma eyes.
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Sedaghat MR, Momeni-Moghaddam H, Gazanchian M, Reinstein DZ, Archer TJ, Randleman JB, Hosseini SR, Nouri-Hosseini G. Corneal Epithelial Thickness Mapping After Photorefractive Keratectomy for Myopia. J Refract Surg 2020; 35:632-641. [PMID: 31610004 DOI: 10.3928/1081597x-20190826-03] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 08/26/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the longitudinal changes in epithelial thickness after photorefractive keratectomy (PRK) and correlate these with refractive changes. METHODS This prospective study included 52 eyes of 52 candidates for myopic PRK. Along with standard ophthalmic examinations, corneal epithelial thickness mapping by anterior segment optical coherence tomography was performed. Epithelial thickness maps of 9-mm diameter were divided into 25 sectors, including a central 2-mm zone and eight octants within para-central (2 to 5 mm), midperipheral (5 to 7 mm), and peripheral (7 to 9 mm) annular zones. All PRK treatments were performed using the Technolas Teneo 317 model 2 excimer laser (Bausch & Lomb, Rochester, NY) and an aspheric profile with a 6-mm diameter optical zone. Follow-up was at 1, 3, and 6 months. RESULTS Repeated thickness measures before and after PRK at different follow-up times showed a significant difference in thickness separately in various zones (P < .001). A significant decrease in thickness was seen 1 month after PRK in all zones. Afterward, epithelial thickening continued in all zones and reached the preoperative thickness in the midperipheral and peripheral zones 6 months later, whereas the thickness in the central 5-mm zone was significantly thicker than before surgery. There was also a significant correlation between changes in spherical equivalent and epithelial thickness from before to 6 months postoperatively in the paracentral and peripheral zones. CONCLUSIONS There was a marked decrease in the epithelial thickening pattern at 1 month after PRK, with gradual thickening at 3 and 6 months. Changes in epithelial thickness and spherical equivalent were significant only for the para-central peripheral zone. [J Refract Surg. 2019;35(10):632-641.].
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Repeatability and comparison of new Corvis ST parameters in normal and keratoconus eyes. Sci Rep 2019; 9:15379. [PMID: 31653884 PMCID: PMC6814725 DOI: 10.1038/s41598-019-51502-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 10/02/2019] [Indexed: 12/28/2022] Open
Abstract
To evaluate the repeatability of corneal biomechanical parameters in normal and keratoconus eyes, and explore factors that affects the repeatability, and further assess the diagnostic ability of new parameters. Seventy-seven keratoconus eyes of 47 patients and 77 right eyes of 77 normal subjects were recruited in current study. All participants received three repeated measurements with 2 to 5 minutes interval. The interclass correlation coefficient (ICC), Cronbach' α and repeatability coefficient (RC) were evaluated. The liner regression analysis was used to identify factors that affect the repeatability, and linear mixed effects model was performed to compare the parameters differences. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic ability of new parameters. Eighteen parameters in normal eyes and twenty-two parameters in keratoconus eyes showed excellent repeatability (ICC ≥ 0.90). Age, axial measurement (AL), spherical equivalent, astigmatism, gender, mean keratometry (Kmean), intraocular pressure (IOP) and central corneal thickness (CCT) could affect the repeatability of new Corvis ST parameters. Compared with normal eyes, the Ambrósio's Relational Thickness horizontal (ARTh), biomechanical corrected IOP (bIOP), stiffness parameter at first applanation (SP A1) were low and the Max Inverse Radius, deformation amplitude (DA) Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Integrated Radius and Corvis Biomechanical Index (CBI) were high in keratoconus eyes (All P < 0.05). Both ARTh and CBI had high Youden index (0.870), and the corresponding cut-off values were 379.29 and 0.44. The repeatability of Corvis ST parameters was acceptable both in normal and keratoconus eyes, and new parameters could effectively diagnose keratoconus eyes from normal eyes.
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Shilova NF, Nahum Y, Adler A, Bahar I, Malyugin BE, Anisimova NS, Livny E. Comparative analysis of biomechanical parameters of the corneas following Descemet membrane endothelial keratoplasty and contralateral healthy corneas. Graefes Arch Clin Exp Ophthalmol 2019; 257:1925-1929. [PMID: 31187244 DOI: 10.1007/s00417-019-04387-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 05/22/2019] [Accepted: 05/31/2019] [Indexed: 10/26/2022] Open
Abstract
PURPOSE To compare the biomechanical properties of the unilateral operated corneas in patients who had undergone Descemet membrane endothelial keratoplasty (DMEK) for pseudophakic bullous keratopathy (PBK) with those of the contralateral normal corneas. METHODS This was a retrospective cohort study conducted at university hospitals (Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel, and S. Fyodorov Eye Microsurgery State Institution, Moscow, Russia). Forty eyes of 20 patients who underwent DMEK for unilateral PBK 3.5 to 36 months ago and with normal fellow eyes were included in the study. An ocular response analyzer was used to measure the corneal biomechanical properties in the operated and normal fellow eyes. The main outcome measures were corneal hysteresis (CH) and corneal resistance factor (CRF). RESULTS The mean CH (8.4 ± 1.5 mmHg vs. 8.2 ± 1.5 mmHg, P = 0.707) and the mean CRF (8.7 ± 1.6 mmHg vs. 8.3 ± 1.6 mmHg, P = 0.419) values did not show any statistically significant difference between the operated and the normal fellow eyes. CONCLUSIONS In our study, the corneas that underwent DMEK for PBK showed normal values for biomechanical parameters. These findings support the previous studies that have reported near complete visual, functional, and ultra-structural rehabilitation of the corneas following DMEK.
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Affiliation(s)
| | - Yoav Nahum
- Department of Ophthalmology, Rabin Medical Center, Petah Tikva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Avital Adler
- Department of Ophthalmology, Rabin Medical Center, Petah Tikva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Irit Bahar
- Department of Ophthalmology, Rabin Medical Center, Petah Tikva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | | | - Eitan Livny
- Department of Ophthalmology, Rabin Medical Center, Petah Tikva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Wu C, Aglyamov SR, Han Z, Singh M, Liu CH, Larin KV. Assessing the biomechanical properties of the porcine crystalline lens as a function of intraocular pressure with optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2018; 9:6455-6466. [PMID: 31065442 PMCID: PMC6491010 DOI: 10.1364/boe.9.006455] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/11/2018] [Accepted: 11/14/2018] [Indexed: 05/04/2023]
Abstract
In this study, we investigated the relationship between the biomechanical properties of the crystalline lens and intraocular pressure (IOP) using a confocal acoustic radiation force (ARF) and phase-sensitive optical coherence elastography (OCE) system. ARF induced a small displacement at the apex of porcine lenses in situ at various artificially controlled IOPs. Maximum displacement, relaxation rate, and Young's modulus were utilized to assess the stiffness of the crystalline lens. The results showed that the stiffness of the crystalline increased as IOP increased, but the lens stiffening was not as significant as the stiffening of other ocular tissues such as the cornea and the sclera. A mechanical hysteresis in the lens was also observed while cycling IOP, indicating that the viscoelastic response of the lens is crucial to fully understanding its biomechanical properties.
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Affiliation(s)
- Chen Wu
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
| | - Salavat R Aglyamov
- Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA
- Department of Biomedical Engineering, University of Texas, Austin, TX 78712, USA
| | - Zhaolong Han
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
- School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
| | - Chih-Hao Liu
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
| | - Kirill V Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
- Interdisciplinary Laboratory of Biophotonics, Tomsk State University, Tomsk, Russia
- Molecular Physiology and Biophysics, Baylor College of Medicine, TX 77584, USA
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Razeghinejad MR, Lee D. Managing normal tension glaucoma by lowering the intraocular pressure. Surv Ophthalmol 2018; 64:111-116. [PMID: 30300624 DOI: 10.1016/j.survophthal.2018.07.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 07/23/2018] [Accepted: 07/30/2018] [Indexed: 11/28/2022]
Affiliation(s)
| | - Daniel Lee
- Wills Eye Hospital, Glaucoma Service, Philadelphia, Pennsylvania, USA.
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Sayed MS, Lee RK. Corneal Biomechanical Properties and Their Role in Glaucoma Diagnosis and Management. Int Ophthalmol Clin 2018; 58:35-49. [PMID: 29870409 DOI: 10.1097/iio.0000000000000233] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Hashemi H, Mohammadi M, Zandvakil N, Khabazkhoob M, Emamian MH, Shariati M, Fotouhi A. Prevalence and risk factors of glaucoma in an adult population from Shahroud, Iran. J Curr Ophthalmol 2018; 31:366-372. [PMID: 31844784 PMCID: PMC6896457 DOI: 10.1016/j.joco.2018.05.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 05/13/2018] [Accepted: 05/20/2018] [Indexed: 01/19/2023] Open
Abstract
Purpose To determine the prevalence of glaucoma and its risk factors in a 40- to 64-year-old Iranian population. Methods In this cross-sectional study, 6311 individuals between the ages of 40–64 years old in Shahroud, a northeastern city in Iran, were selected through multistage cluster sampling. All participants underwent eye exams, optometry, and imaging. They had stereoscopic optic disc photography, visual field evaluation, and their intraocular pressure (IOP) was measured by ophthalmologists before pupil dilation. Glaucoma was defined by the standardized criteria, offered by the International Society for Geographical and Epidemiological Ophthalmology (ISGEO). Results Of the 5190 people who participated in the study (82.2%), data from 4637 people were used in the analysis. The prevalence of glaucoma was 1.92% [95% confidence intervals (CI): 1.53–2.31]; 1.4% (95% CI: 0.96–1.84) in women and 2.62% (95% CI: 1.95–3.28) in men. Glaucoma prevalence was 0.9% in the 40–44 years age group, and significantly increased to 3.55% in the 60–64 years age group. In the multiple logistic regression model, age [odds ratio (OR) = 1.08, 95% CI: 1.05–1.12], IOP (OR = 1.04, 95% CI: 1.01–1.06), axial length (OR = 1.34, 95% CI: 1.1–1.63), corneal radius of curvature (OR = 2.76, 95% CI: 1.26–6.06), and corneal diameter (OR = 0.63, 95% CI: 0.46–0.87) showed significant statistical association with glaucoma. Conclusions The prevalence of glaucoma was considerably high at older ages. Major risk factors confirmed by this study included older age and high IOP. Certain ocular biometric components such as the axial length and the corneal radius of curvature must be noted as important glaucoma risk factors at younger ages.
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Affiliation(s)
- Hassan Hashemi
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
| | | | - Narges Zandvakil
- Farabi Eye Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehdi Khabazkhoob
- Department of Medical Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Hassan Emamian
- Center for Health Related Social and Behavioral Sciences Research, Shahroud University of Medical Sciences, Shahroud, Iran
| | - Mohammad Shariati
- Department of Community Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Akbar Fotouhi
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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Lamina Cribrosa Thickness in Patients With Keratoconus. Cornea 2018; 37:e28-e29. [DOI: 10.1097/ico.0000000000001536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Chen M, Kueny L, Schwartz AL. The role of corneal hysteresis during the evaluation of patients with possible normal-tension glaucoma. Clin Ophthalmol 2018; 12:555-559. [PMID: 29606853 PMCID: PMC5868619 DOI: 10.2147/opth.s161675] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose There are multiple reports of the role of corneal hysteresis (CH) as an independent risk factor for the diagnosis and risk of progression of normal-tension glaucoma (NTG). Our study measured CH with the Ocular Response Analyzer (ORA) in patients with intraocular pressure (IOP) <21 mmHg to investigate if a low CH would identify NTG in this Asian-based practice. Methods This was a prospective cross-sectional study of patients who underwent routine eye examination during 2016 in a private practice in Honolulu, Hawaii, where most patients are Asian. Inclusion criteria are: 1) ≥65 years 2) IOP <21 (compensated IOP by ORA), and 3) CH values <10 using ORA as measured by a single experienced technician. Exclusion criteria are: 1) sight-limiting ocular or corneal disease that would preclude accurate measurements for the purposes of the study. 2) Any patient who had difficulty in being tested with the ORA. 3) Patients who had any history of any type of glaucoma. All patients that met the inclusion criteria underwent fundus photography to measure cup-to-disc ratio and cup-to-disc asymmetry and also had central corneal thickness measured. Thickness of the retina nerve fiber layer was measured by ocular coherence tomography. The eyes with an average retina nerve fiber layer thickness less than 80 μm were classified as possible NTG and were scheduled for a visual field test. The field examination was considered valid only if the fixation, false positives, and false negatives were within the acceptable range. Patient demographics and data on preexisting diseases were collected including age, sex, coexisting medical conditions, and previous intraocular surgery. Those with thinning of retina nerve fiber layer on optical coherence tomography had a Humphrey visual field test to confirm the diagnosis of glaucoma. Results Seventy-six eyes of 46 patients that met the eligibility criteria were included in the study. Twenty-one previously undiagnosed eyes were confirmed as having NTG, which corresponds to an incidence of 27.6%. Conclusion CH measurement is a valuable test to assist in early diagnosis of NTG, especially in the elderly Asian population. With an established diagnosis, aggressive early treatments medically or surgically to further lower IOP can prevent irreversible blindness, which can severely impact the patient’s family and socioeconomic status.
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Affiliation(s)
- Ming Chen
- Department of Surgery, Division of Ophthalmology, University of Hawaii, Honolulu, HI, USA
| | - Laura Kueny
- Department of Ophthalmology, Georgetown University, Washington, DC, USA
| | - Arthur L Schwartz
- Department of Ophthalmology, Georgetown University, Washington, DC, USA
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Gizzi C, Cellini M, Campos EC. In vivo assessment of changes in corneal hysteresis and lamina cribrosa position during acute intraocular pressure elevation in eyes with markedly asymmetrical glaucoma. Clin Ophthalmol 2018; 12:481-492. [PMID: 29588569 PMCID: PMC5858548 DOI: 10.2147/opth.s151532] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Purpose To investigate the biomechanical response of the cornea, lamina cribrosa (LC), and prelaminar tissue (PT) to an acute intraocular pressure (IOP) increase in patients with markedly asymmetrical glaucoma and in healthy controls. Patients and methods A total of 24 eyes of 12 patients with markedly asymmetrical primary open-angle glaucoma (POAG) and 12 eyes of 12 healthy patients were examined with spectral-domain optical coherence tomography (SD-OCT) and ocular response analyzer (ORA) at baseline and during acute IOP elevation by means of an ophthalmodynamometer. The displacement of the LC and PT and the change in corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated. Results Following a mean IOP increase of 12.3±2.4 mmHg, eyes with severe glaucoma demonstrated an overall mean anterior displacement of the LC (−6.58±26.09 µm) as opposed to the posterior laminar displacement in eyes with mild glaucoma (29.08±19.28 µm) and in healthy eyes (30.3±10.9; p≤0.001 and p=0.001, respectively). The PT displaced posteriorly during IOP elevation in all eyes. The CH decreased in eyes with severe glaucoma during IOP elevation (from 9.30±3.65 to 6.92±3.04 mmHg; p=0.012), whereas the CRF increased markedly in eyes with mild glaucoma (from 8.61±2.30 to 12.38±3.64; p=0.002) and in eyes with severe glaucoma (from 9.02±1.48 to 15.20±2.06; p=0.002). The increase in CRF correlated with the anterior displacement of the LC in eyes with severe glaucoma. Conclusion Eyes with severe glaucoma exhibited a mean overall anterior displacement of the anterior laminar surface, while eyes with mild glaucoma and healthy eyes showed a posterior displacement of the LC during IOP elevation. The CH decreased significantly from baseline only in eyes with severe glaucoma, but the CRF increased significantly in all glaucomatous eyes. The CRF increase correlated with the anterior displacement of the LC in eyes with severe glaucoma.
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Affiliation(s)
- Corrado Gizzi
- Department of Experimental, Diagnostic and Speciality Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy
| | - Mauro Cellini
- Department of Experimental, Diagnostic and Speciality Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy
| | - Emilio C Campos
- Department of Experimental, Diagnostic and Speciality Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy
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Belovay GW, Goldberg I. The thick and thin of the central corneal thickness in glaucoma. Eye (Lond) 2018; 32:915-923. [PMID: 29445115 DOI: 10.1038/s41433-018-0033-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/15/2018] [Accepted: 01/17/2018] [Indexed: 11/09/2022] Open
Abstract
Central corneal thickness (CCT) is an important parameter in the assessment of any potential glaucoma patient. While it affects prognosis in ocular hypertension, its value in patients diagnosed with glaucoma is less certain. There are several biological factors and genetic components that may influence glaucoma progression, which have been associated with thinner CCT. The CCT itself can be affected by several factors including ethnicity, age, sex, glaucoma medications, genetics, and the subtype of glaucoma. Besides, there is variability in the measurement of CCT between difference types of devices. These factors need to be considered in the evaluation of glaucoma patients' CCT and its effect on interpretation of intraocular pressure levels and risk stratification.
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Affiliation(s)
| | - Ivan Goldberg
- Glaucoma Unit, Sydney Eye Hospital, Sydney, Australia.,Discipline of Ophthalmology, University of Sydney, Sydney, Australia.,Eye Associates, Sydney, Australia
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Relationship between corneal biomechanical properties and structural biomarkers in patients with normal-tension glaucoma: a retrospective study. BMC Ophthalmol 2018; 18:7. [PMID: 29334923 PMCID: PMC5769305 DOI: 10.1186/s12886-018-0673-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Accepted: 01/04/2018] [Indexed: 11/10/2022] Open
Abstract
Background We evaluated the relationships between corneal biomechanical properties and structural parameters in patients with newly diagnosed, untreated normal-tension glaucoma (NTG). Methods All subjects were evaluated using an Ocular Response Analyzer (ORA) measuring corneal hysteresis (CH) and the corneal resistance factor (CRF). Central corneal thickness (CCT), Goldmann applanation tonometric (GAT) data, axial length, and the spherical equivalent (SE), were also measured. Confocal scanning laser ophthalmoscopy was performed with the aid of a Heidelberg retina tomograph (HRT III). We sought correlations between HRT parameters and different variables including CCT, CH, and the CRF. Multiple linear regression analysis was performed to identify significant associations between corneal biomechanical properties and optic nerve head parameters. Results We enrolled 95 eyes of 95 NTG patients and 93 eyes of 93 normal subjects. CH and the CRF were significantly lower in more advanced glaucomatous eyes (P = 0.001, P = 0.008, respectively). The rim area, rim volume, linear cup-to-disc ratio (LCDR), and mean retinal nerve fiber layer (RNFL) thickness were significantly worse in more advanced glaucomatous eyes (P < 0.001, P < 0.001, P < 0.001, and P = 0.001). CH was directly associated with rim area, rim volume, and mean RNFL thickness (P = 0.012, P = 0.028, and P = 0.043) and inversely associated with LCDR (P = 0.015), after adjusting for age, axial length, CCT, disc area, GAT data, and SE. However, in normal subjects, there were no significant associations between corneal biomechanical properties and HRT parameters. Conclusions A lower CH is significantly associated with a smaller rim area and volume, a thinner RNFL, and a larger LCDR, independent of disc size, corneal thickness, intraocular pressure, and age.
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Miki A, Maeda N, Asai T, Ikuno Y, Nishida K. Measurement repeatability of the dynamic Scheimpflug analyzer. Jpn J Ophthalmol 2017; 61:433-440. [PMID: 28983780 DOI: 10.1007/s10384-017-0534-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 07/28/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE To evaluate the repeatability of corneal deformation parameters measured using a dynamic Scheimpflug analyzer and the impact of baseline clinical factors on the repeatability of each parameter. STUDY DESIGN Retrospective, cross-sectional study. METHODS Forty-eight eyes (48 healthy subjects; mean age, 49.0 ± 19.5 years) underwent repeated examinations with the Scheimpflug analyzer to evaluate the test-retest variability. The intraclass correlation coefficient (ICC) and repeatability coefficient as indicators of variability were computed for 35 parameters measured with the Scheimpflug analyzer. The associations between the magnitude of the test-retest variability and baseline factors, such as age, axial length (AL), intraocular pressure (IOP), and central corneal thickness (CCT), were analyzed. RESULTS The test-retest repeatability was excellent for 22 (62.9%) of 35 parameters (ICC ≥ 0.75), good for seven (20%), (ICC ≥ 0.6), fair for four (11.4%), (ICC ≥ 0.4), and poor for two (5.7%) parameters (ICC < 0.4). Age was associated positively with the magnitude of variability in 13 (37.1%) parameters; measurement variability was affected significantly by AL (5 parameters, 14.3%) and CCT (7 parameters, 20%) but, except for one parameter not by IOP. CONCLUSION Most parameters of the dynamic Scheimpflug analyzer showed favorable measurement reliability in healthy subjects. However, six parameters showed poor-to-fair repeatability. Age, AL, and CCT significantly affected the repeatability of several parameters. These results should be considered when clinicians use this device in clinical practice.
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Affiliation(s)
- Atsuya Miki
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan.
| | - Naoyuki Maeda
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan
| | - Tomoko Asai
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan
| | - Yasushi Ikuno
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan
| | - Kohji Nishida
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka, 565-0871, Japan
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Hirasawa K, Matsuura M, Murata H, Nakakura S, Nakao Y, Kiuchi Y, Asaoka R. Association between Corneal Biomechanical Properties with Ocular Response Analyzer and Also CorvisST Tonometry, and Glaucomatous Visual Field Severity. Transl Vis Sci Technol 2017. [PMID: 28626602 PMCID: PMC5472364 DOI: 10.1167/tvst.6.3.18] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate the association between corneal biomechanical properties measured with the Ocular Response Analyzer (ORA) and also CorvisST (CST) tonometry, and glaucomatous visual field (VF) severity. Methods One hundred forty-six eyes of 91 patients with primary open-angle glaucoma who performed Humphrey Field Analyzer 30-2 or 24-2 SITA-Standard, ORA, and CST within 180 days were included in this multicentral, observational cross-sectional study. The association between ORA parameters (corneal hysteresis [CH] and corneal resistant factor [CRF]), CST parameters (A1 and A2 time, A1 and A2 length, A1 and A2 velocity, A1 and A2 deformation amplitude, highest deformation amplitude, highest concavity time, peak distance, and radius), and other basic parameters (age, intraocular pressure with Goldmann applanation tonometry, central corneal thickness, and axial length) against mean total deviation (mTD) were analyzed using a linear mixed-model and model selection with corrected Akaike Information Criterion (AICc). Results The optimal model of VF severity included ORA's CH as well as a number of CST parameters, including A1 length, A2 time, radius, and highest concavity deformation amplitude (AICc: 971.7). The possibility this model describes visual field severity more accurately than the optimal model without CST parameters was 99.98%. Conclusion Glaucomatous VF severity was best described by both ORA and CST parameters. Eyes with corneas that experience sharp and deep indentation at the maximum deformation, wide indentation at the first applanation, and early second applanation in the CST measurement are more likely to show advanced VF severity. Translational Relevance CorvisST tonometry parameters are related to VF severity in glaucoma patients.
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Affiliation(s)
- Kazunori Hirasawa
- Department of Ophthalmology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan.,Department of Orthoptics and Visual Science, School of Allied Health Sciences, Kitasato University, Kanagawa, Japan
| | - Masato Matsuura
- Department of Ophthalmology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
| | - Hiroshi Murata
- Department of Ophthalmology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
| | - Shunsuke Nakakura
- Department of Ophthalmology, Saneikai Tsukazaki Hospital, Hyogo, Japan
| | - Yoshitaka Nakao
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima, Japan
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima, Japan
| | - Ryo Asaoka
- Department of Ophthalmology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
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Comparison of Corneal Biomechanical Properties between Indian and Chinese Adults. Ophthalmology 2017; 124:1271-1279. [PMID: 28461014 DOI: 10.1016/j.ophtha.2017.03.055] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 03/29/2017] [Accepted: 03/29/2017] [Indexed: 01/31/2023] Open
Abstract
PURPOSE To investigate the difference in corneal hysteresis (CH) and corneal resistance factor (CRF) between Indian and Chinese populations. DESIGN Population-based cross-sectional study. PARTICIPANTS Three hundred eighty-two Singaporean Indian persons and 764 Singaporean Chinese 50 years of age or older were included from the Singapore Indian Eye Study and Singapore Chinese Eye Study, respectively. METHODS Participants underwent standardized systemic and ocular examinations and interviewer-administered questionnaires for risk factor assessment. The CH and CRF were measured with the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, NY). Information on genetic ancestry was derived using principal component analysis. Linear regression models were used to investigate the association of CH and CRF with potential risk factors. MAIN OUTCOME MEASURES Corneal hysteresis and CRF. RESULTS After excluding participants with a history of intraocular surgery, a diagnosis of glaucoma suspect or glaucoma, refractive surgery, or presence of corneal abnormalities, CH and CRF readings were available for 382 Indian persons. For each Indian participant, 2 Chinese participants were selected and matched for age and gender (n = 764). There were no differences in the clinical measurements of CH (10.6±1.6 mmHg; P = 0.670) or CRF (10.3±1.7 mmHg; P = 0.103) between the ethnic groups. However, after adjusting for covariates, Indian persons had, on average, 0.18-mmHg higher CH levels than in Chinese (95% confidence interval [CI], 0.02-0.38; P = 0.031). Consistently, CH level was correlated significantly with genetic ancestry in the Southeast Asian population. Corneal resistance factor level was not associated independently with self-reported ethnicity (95% CI, -0.10 to 0.29; P = 0.335). CONCLUSIONS Chinese have lower CH than Indian persons, and this disparity may reflect biomechanical differences of the cornea.
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Li BB, Cai Y, Pan YZ, Li M, Qiao RH, Fang Y, Tian T. Corneal Biomechanical Parameters and Asymmetric Visual Field Damage in Patients with Untreated Normal Tension Glaucoma. Chin Med J (Engl) 2017; 130:334-339. [PMID: 28139518 PMCID: PMC5308017 DOI: 10.4103/0366-6999.198920] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Background: High intraocular pressure (IOP) and low central corneal thickness (CCT) are important validated risk factors for glaucoma, and some studies also have suggested that eyes with more deformable corneas may be in higher risk of the development and worsening of glaucoma. In the present study, we aimed to evaluate the association between corneal biomechanical parameters and asymmetric visual field (VF) damage using a Corvis-ST device in patients with untreated normal tension glaucoma (NTG). Methods: In this observational, cross-sectional study, 44 newly diagnosed NTG patients were enrolled. Of these, 31 had asymmetric VF damage, which was defined as a 5-point difference between the eyes according to the Advanced Glaucoma Intervention Study scoring system. Corneal biomechanical parameters were obtained using a Corvis-ST device, such as time from start until the first and second applanation is reached (time A1 and time A2, respectively), cord length of the first and second applanation (length A1 and length A2, respectively), corneal speed during the first and second applanation (velocity A1 and velocity A2, respectively), time from start until highest concavity is reached (time HC), maximum amplitude at the apex of highest concavity (def ampl HC), distance between the two peaks at highest concavity (peak dist HC), and central concave curvature at its highest concavity (radius HC). Results: Time A1 (7.19 ± 0.28 vs. 7.37 ± 0.41 ms, P = 0.010), length A1 (1.73 [1.70–1.76] vs. 1.78 [1.76–1.79] mm, P = 0.007), length A2 (1.58 [1.46–1.70] vs. 1.84 [1.76–1.92] mm, P < 0.001), peak dist HC (3.53 [3.08–4.00] vs. 4.33 [3.92–4.74] mm, P = 0.010), and radius HC (6.20 ± 0.69 vs. 6.59 ± 1.18 mm, P = 0.032) were significantly lower in the worse eyes than in the better eyes, whereas velocity A1 and def ampl HC were significantly higher (0.156 [0.149–0.163] vs. 0.145 [0.138–0.152] m/s, P = 0.002 and 1.19 ± 0.13 vs. 1.15 ± 0.13 mm, P = 0.005, respectively). There was no significant difference in time A2, velocity A2, and time HC between the two groups. In addition, no difference was observed in IOP, CCT, and axial length. In the univariate and multivariate analyses, some of the Corvis-ST parameters, including time A1 and def ampl HC, were correlated with known risk factors for glaucoma, and there was also a significant positive correlation between def ampl HC and age. Conclusions: There were differences in dynamic corneal response parameters but not IOP or CCT between the paired eyes of NTG patients with asymmetric VF damage. We suggest that the shape of the cornea is more easily altered in the worse eyes of asymmetric NTG patients.
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Affiliation(s)
- Bai-Bing Li
- Department of Ophthalmology, Peking University First Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing 100034, China
| | - Yu Cai
- Department of Ophthalmology, Peking University First Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing 100034, China
| | - Ying-Zi Pan
- Department of Ophthalmology, Peking University First Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing 100034, China
| | - Mei Li
- Department of Ophthalmology, Peking University First Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing 100034, China
| | - Rong-Hua Qiao
- Department of Ophthalmology, Beijing Tsinghua Changgung Hospital, Beijing 102218, China
| | - Yuan Fang
- Department of Ophthalmology, Peking University First Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing 100034, China
| | - Tian Tian
- Department of Ophthalmology, Peking University First Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing 100034, China
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Abstract
PURPOSE OF REVIEW The purpose of this review is to summarize the role of central corneal thickness (CCT) in the clinical management of a glaucoma patient. RECENT FINDINGS The prognostic value of CCT is well recognized in patients with ocular hypertension. However, its predictive value in other glaucoma suspects and patients with established glaucoma is less certain. Tonometry artefacts can result from variations in CCT. However, an adequately validated correction algorithm for Goldmann applanation tonometry measurements does not exist. Newer methods of tonometry are potentially less influenced by CCT but are limited in their clinical use. There may also be biological and genetic associations between corneal thickness and glaucoma. Demographics, environmental factors, glaucoma treatment and the measurement device used have a significant influence on CCT, and should be considered when interpreting the effect of cornea thickness in patients with glaucoma. New measurements of the biomechanical properties of the cornea are likely to be better approximations of the globe biomechanics than CCT, but these require further evaluation. SUMMARY The clinical significance of CCT is well recognized in the context of glaucoma diagnosis and management, though the extent of its importance remains debatable. Corneal biomechanical properties may be more significantly associated with glaucoma than CCT.
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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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Simsek T, Soba DO, Tırhış MH, Yılmazbaş P, Öztürk F. Evaluation of corneal biomechanical properties using an ocular response analyser to examine aphakic and pseudophakic patients after congenital cataract surgery. Acta Ophthalmol 2016; 94:e198-203. [PMID: 26521752 DOI: 10.1111/aos.12900] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 09/02/2015] [Indexed: 01/01/2023]
Abstract
PURPOSE We evaluated corneal biomechanical properties in aphakic and pseudophakic patients after congenital cataract surgery and compared the data with those of age-matched normal subjects. METHODS We included 43 eyes of 43 aphakic or pseudophakic patients treated via congenital cataract surgery. As controls, 42 healthy age- and sex-matched subjects were enrolled. After a complete ophthalmic examination, central corneal thickness (CCT) and intraocular pressure (IOP) were determined. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated IOP (IOPcc) and Goldmann-correlated IOP (IOPg) were recorded using an ocular response analyser. RESULTS In the study group, 18 eyes were aphakic and 25 eyes pseudophakic. We found a significant difference in CCT between the aphakic, pseudophakic and control groups (p < 0.001). No significant among-group differences were detected in CH or CRF (p > 0.05). We found significant differences in IOPcc, IOPg and IOP measured with Goldmann applanation tonometry (IOPGAT ) between the study and control groups (p < 0.001). In contrast, we found no significant differences within the two study groups in terms of these three IOP values (p > 0.05). CONCLUSION Although CCT increased after congenital cataract surgery, corneal biomechanical parameters, including CH and the CRF, were not affected by such surgery. Determination of the IOPcc did not provide any additional information on true IOP, which was independent of CCT in both aphakic and pseudophakic patients after congenital cataract surgery.
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Affiliation(s)
- Tulay Simsek
- Department of Ophthalmology; Eskişehir Osmangazi University; School of Medicine; Eskişehir Turkey
| | | | | | | | - Faruk Öztürk
- Department of Ophthalmology; Hacettepe University; School of Medicine; Ankara Turkey
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Abstract
Purpose We aimed to assess corneal biomechanics using the ocular response analyzer in patients with normal-tension glaucoma (NTG), and to evaluate the relationship between corneal biomechanics and visual field loss. Methods This was a prospective observational case series including patients with bilateral asymmetric NTG. For all patients, corneal hysteresis (CH), corneal resistance factor (CRF), CH − CRF difference, and central corneal thickness values were matched against the mean deviation (MD) of the visual field and the cup/disc ratio. For paired-eye comparison in each patient, both eyes were categorized into a better-eyes group and a worse-eyes group according to lower and higher corneal-compensated intraocular pressure readings, respectively. Statistical analysis was carried out with the independent-samples Student’s t-test, and the level of statistical significance was set at 0.05. Correlation was assessed using Pearson’s correlation coefficient. Results The study included 240 eyes of 120 patients. CH was inversely proportional to the MD in the visual field (P=0.01). CRF in both eyes was inversely proportional to the MD of the visual field (P=0.01). CH − CRF difference was directly proportional to the MD of the visual field (P=0.01). For paired-eye comparison, lower corneal-compensated intraocular pressure was associated with higher CH, higher CRF, smaller cup/disc ratio, and less deterioration of MD of visual field. Conclusion CH, CRF, and CH − CRF are more powerful predictors of NTG progression than central corneal thickness.
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Affiliation(s)
- Hazem Helmy
- Department of Glaucoma and Optic Nerve Diseases, Research Institute of Ophthalmology, Cairo, Egypt
| | - Mahmoud Leila
- Retina Department, Research Institute of Ophthalmology, Cairo, Egypt
| | - Ahmed Atef Zaki
- Corneal Diseases Department, Research Institute of Ophthalmology, Cairo, Egypt
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Park JY, Lee JW, Shin JH. The Short-Term Effect of Prostaglandin Analog Monotherapy on Corneal Biomechanical Properties in Normal Tension Glaucoma Patients. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2016. [DOI: 10.3341/jkos.2016.57.3.477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Jung Yul Park
- Department of Ophthalmology, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Korea
| | - Ji Woong Lee
- Department of Ophthalmology, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Korea
| | - Jong Hoon Shin
- Department of Ophthalmology, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Korea
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Lam AKC, Hon Y, Leung LKK, Lam DCC. Repeatability of a novel corneal indentation device for corneal biomechanical measurement. Ophthalmic Physiol Opt 2015; 35:455-61. [DOI: 10.1111/opo.12219] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 05/07/2015] [Indexed: 12/01/2022]
Affiliation(s)
- Andrew K. C. Lam
- School of Optometry; The Hong Kong Polytechnic University; Hong Kong
| | - Ying Hon
- School of Optometry; The Hong Kong Polytechnic University; Hong Kong
| | - Leo K. K. Leung
- Department of Mechanical and Aerospace Engineering; The Hong Kong University of Science and Technology; Hong Kong
| | - David C. C. Lam
- Department of Mechanical and Aerospace Engineering; The Hong Kong University of Science and Technology; Hong Kong
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Association between corneal hysteresis and the magnitude of intraocular pressure decrease after cataract surgery. J Cataract Refract Surg 2015; 41:1176-81. [DOI: 10.1016/j.jcrs.2014.09.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 08/26/2014] [Accepted: 09/01/2014] [Indexed: 11/16/2022]
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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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Abstract
PURPOSE OF REVIEW Glaucoma is a leading cause of irreversible blindness worldwide. It is estimated that roughly 60.5 million people had glaucoma in 2010 and that this number is increasing. Many patients continue to lose vision despite apparent disease control according to traditional risk factors. The purpose of this review is to discuss the recent findings with regard to corneal hysteresis, a variable that is thought to be associated with the risk and progression of glaucoma. RECENT FINDINGS Low corneal hysteresis is associated with optic nerve and visual field damage in glaucoma and the risk of structural and functional glaucoma progression. In addition, hysteresis may enhance intraocular pressure (IOP) interpretation: low corneal hysteresis is associated with a larger magnitude of IOP reduction following various glaucoma therapies. Corneal hysteresis is dynamic and may increase in eyes after IOP-lowering interventions are implemented. SUMMARY It is widely accepted that central corneal thickness is a predictive factor for the risk of glaucoma progression. Recent evidence shows that corneal hysteresis also provides valuable information for several aspects of glaucoma management. In fact, corneal hysteresis may be more strongly associated with glaucoma presence, risk of progression, and effectiveness of glaucoma treatments than central corneal thickness.
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Park JH, Jun RM, Choi KR. Significance of corneal biomechanical properties in patients with progressive normal-tension glaucoma. Br J Ophthalmol 2015; 99:746-51. [PMID: 25555704 DOI: 10.1136/bjophthalmol-2014-305962] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 12/05/2014] [Indexed: 11/04/2022]
Abstract
AIM To investigate the clinical significance of corneal biomechanical properties assessed using an ocular response analyser in patients with progressing normal-tension glaucoma (NTG). METHODS In this retrospective study, we included 82 eyes of 82 NTG patients who had been receiving topical anti-glaucoma medications. Patients were allocated to two groups based on the mean value of corneal hysteresis (CH) and the status of progression. The assessment of progression was based on the trend analysis using mean deviation slope. Uni- and multivariable logistic analyses were constructed to identify factors associated with increased odds of progression, including CH, central corneal thickness (CCT), and retinal nerve fibre layer (RNFL) thickness. RESULTS Forty-six eyes (56.1%) reached the progression criteria. Eyes with progression had lower CCT (530.2±38.6 vs 549.4±38.3 μm, p=0.03), thinner average RNFL thickness (70.6±16.1 vs 82.8±17.4 μm, p<0.01), lower CH (9.4±1.3 vs 10.8±1.4 mm Hg, p<0.01), and lower corneal resistance factor (9.3±1.3 vs 10.4±1.8 mm Hg, p<0.01) than eyes without progression. CH and CCT were significantly correlated (r=0.44, p<0.01). Upon multivariable analysis, CH (β (B)=0.32 per mm Hg lower, p<0.01) and average RNFL thickness (β=0.96 per μm lower, p=0.04) remained statistically significant. CONCLUSIONS Corneal biomechanical properties are correlated and associated with the progression of visual field damage in NTG patients. These findings suggest that CH can be used as one of the prognostic factors for progression, independent of corneal thickness or intraocular pressure.
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Affiliation(s)
- Jong Hyuk Park
- Department of Ophthalmology, Institute of Ophthalmology & Optometry, Ewha Womans University School of Medicine, Seoul, Republic of Korea
| | - Roo Min Jun
- Department of Ophthalmology, Institute of Ophthalmology & Optometry, Ewha Womans University School of Medicine, Seoul, Republic of Korea
| | - Kyu-Ryong Choi
- Department of Ophthalmology, Institute of Ophthalmology & Optometry, Ewha Womans University School of Medicine, Seoul, Republic of Korea
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Cho AR, Choi YJ, Rhew JY, Choi KR. Diagnostic Availability of Ocular Response Analyzer in Korean Patients with Normal Tension Glaucoma. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2015. [DOI: 10.3341/jkos.2015.56.1.86] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Ah Ran Cho
- Institute of Ophthalmology and Optometry, Department of Ophthalmology, Ewha Womans University Medical Center, Ewha Womans University School of Medicine, Seoul, Korea
| | - Yun Jeong Choi
- Department of Ophthalmology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Jin Young Rhew
- Institute of Ophthalmology and Optometry, Department of Ophthalmology, Ewha Womans University Medical Center, Ewha Womans University School of Medicine, Seoul, Korea
| | - Kyu Ryong Choi
- Institute of Ophthalmology and Optometry, Department of Ophthalmology, Ewha Womans University Medical Center, Ewha Womans University School of Medicine, Seoul, Korea
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Shin J, Lee JW, Kim EA, Caprioli J. The effect of corneal biomechanical properties on rebound tonometer in patients with normal-tension glaucoma. Am J Ophthalmol 2015; 159:144-54. [PMID: 25308786 DOI: 10.1016/j.ajo.2014.10.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 10/03/2014] [Accepted: 10/04/2014] [Indexed: 11/17/2022]
Abstract
PURPOSE To evaluate the effects of corneal biomechanical properties on intraocular pressure (IOP) measured with the ICare, and to compare IOP readings obtained with ICare, Ocular Response Analyzer (ORA), and Goldmann applanation tonometry (GAT) in normal-tension glaucoma (NTG) and normal subjects. DESIGN Prospective, cross-sectional, comparative study. METHODS IOP was measured with ICare, ORA, and GAT. All subjects had corneal hysteresis (CH) and corneal resistance factor (CRF), which were measured with ORA; and central corneal thickness (CCT), axial length, spherical equivalent, and keratometry. RESULTS This study enrolled 97 eyes of 97 NTG patients and 89 eyes of 89 normal subjects. CCT, CH, and CRF in NTG patients were significantly lower than those in normal subjects (P = .033, P = .006, and P = .003). The difference in IOP between techniques was highly significant in NTG patients (P < .001), while there was no significant difference in IOP values between techniques in normal controls (P = .931). ICare readings were significantly lower than corneal-compensated IOP in NTG patients (P = .014). CH and CRF were significantly associated with IOP measurements with ICare in NTG and normal subjects (P < .001). The greater difference between IOPcc and ICare in NTG patients was significantly influenced by the lower CH (P < .001). CONCLUSIONS Since ICare is a convenient way to measure IOP, ICare is a reasonable option as an alternative tonometer in NTG patients. However, the clinician must consider that the corneal biomechanical characteristics in NTG can cause ICare to underestimate IOP.
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Affiliation(s)
- Jonghoon Shin
- Department of Ophthalmology, Pusan National University Hospital, Busan, South Korea
| | - Ji-Woong Lee
- Department of Ophthalmology, Pusan National University Hospital, Busan, South Korea; Medical Research Institute, Pusan National University Hospital, Busan, South Korea; The Jules Stein Eye Institute, University of California at Los Angeles School of Medicine, Los Angeles, California.
| | - Eun-Ah Kim
- The Jules Stein Eye Institute, University of California at Los Angeles School of Medicine, Los Angeles, California
| | - Joseph Caprioli
- The Jules Stein Eye Institute, University of California at Los Angeles School of Medicine, Los Angeles, California
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