Assessment of Corneal Biomechanical Properties in Normal Tension Glaucoma and Comparison With Open-angle Glaucoma, Ocular Hypertension, and Normal Eyes (original) (raw)
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Journal of Clinical Medicine, 2021
Purpose: To evaluate and compare corneal hysteresis (CH), corneal resistance factor (CRF), and central corneal thickness (CCT), measurements were taken between a healthy population (controls), patients diagnosed with glaucoma (DG), and glaucoma suspect patients due to ocular hypertension (OHT), family history of glaucoma (FHG), or glaucoma-like optic discs (GLD). Additionally, Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated IOP (IOPcc) were compared between the different groups of patients. Methods: In this prospective analytical-observational study, a total of 1065 patients (one eye of each) were recruited to undergo Ocular Response Analyzer (ORA) testing, ultrasound pachymetry, and clinical examination. Corneal biomechanical parameters (CH, CRF), CCT, IOPg, and IOPcc were measured in the control group (n = 574) and the other groups: DG (n = 147), FHG (n = 78), GLD (n = 90), and OHT (n = 176). We performed a variance analysis (ANOVA) for all the dependent va...
American Journal of Ophthalmology
PURPOSE: To evaluate corneal biomechanical properties across the glaucoma spectrum and study the relationship between these measurements and intraocular pressure measured by Goldmann applanation tonometry (GAT-IOP) and central corneal thickness (CCT). • DESIGN: Prospective cross-sectional study. • METHODS: SETTING: Tertiary-care teaching institute. STUDY POPULATION: A total of 323 eyes of 323 participants (71 normal, 101 glaucoma suspect [GS], 38 ocular hypertension [OHT], 59 primary angle-closure disease [PACD], 36 primary open-angle glaucoma [POAG], and 18 normal-tension glaucoma [NTG]) who had received no ophthalmic treatment. OBSERVATION PROCEDURES: Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) measured by the Ocular Response Analyzer (ORA). GAT-IOP and CCT recorded in all subjects. MAIN OUTCOME MEASURES: Regression analysis used to determine the relationship between GAT-IOP, CCT, age, CRF, and CH. Bland-Altman plots used to assess agreement between IOP measured by GAT and the ORA (IOPg).
Association Between Corneal Biomechanical Properties and Glaucoma Severity
American Journal of Ophthalmology, 2012
To investigate the association between corneal biomechanical parameters using the Ocular Response Analyzer (ORA) and glaucoma severity. • DESIGN: Observational cross-sectional study. • METHODS: Two hundred ninety-nine eyes of 191 patients with confirmed or suspect glaucoma were recruited at the University of California, San Diego. Corneal hysteresis (CH) and corneal resistance factor (CRF) were obtained from all participants. Standard automated perimetry was done using the 24-2 Swedish Interactive Threshold Algorithm. Retinal nerve fiber layer (RNFL) thickness measurements were obtained using GDx ECC and spectral-domain optical coherence tomography (SD-OCT). The association between ORA parameters and disease severity was evaluated using univariable and multivariable regression models. • RESULTS: CH and CRF were both positively associated with mean defect (MD) (R 2 ؍ 0.03; P < .01 and R 2 ؍ 0.10; P < .01, respectively). In multivariable analysis, the association between CRF and MD remained significant while CH to MD did not (P < .01 and P ؍ .77). In the GDx ECC subgroup (204 eyes), there was a weak association between CH and CRF and average RNFL thickness (R 2 ؍ 0.07; P < .01 and R 2 ؍ 0.05; P < .01, respectively), which was not observed in the SD-OCT subgroup (146 eyes) (R 2 ؍ 0.01; P ؍ .30 and R 2 ؍ 0.01; P ؍ .21). After adjusting for central corneal thickness, age, and axial length, the relationship of CH and CRF to RNFL thickness no longer reached statistical significance. • CONCLUSIONS: The current study found only a weak relationship between corneal biomechanical parameters and measures of structural and functional damage in glaucoma.
Clinical Ophthalmology, 2022
Background: To evaluate biomechanical parameters of the cornea provided by Corvis ST in patients with ocular hypertension, primary open-angle glaucoma, and amyloidotic glaucoma and to compare with healthy controls. Methods: This was a cross-sectional study of patients with ocular hypertension, primary open-angle glaucoma, and amyloidotic glaucoma that underwent Corvis ST imaging. Primary outcome was the comparison of corneal biomechanical parameters between study groups after adjusting for age, gender, Goldmann intraocular pressure (GAT-IOP), and prostaglandin analogues medication. Secondary outcome was the comparison of different IOP measurements in each group. Results: One hundred and eighty-three eyes from 115 patients were included: 61 with primary open-angle glaucoma, 32 with amyloidotic glaucoma, 37 with ocular hypertension and 53 were healthy controls. Amyloidotic glaucoma group had smaller radius (p=0.025), lower deflection amplitude at highest concavity (p=0.019), and higher integrated radius (p=0.014) than controls. Ocular hypertension group had higher stiffness parameter at first applanation (p=0.043) than those with primary open-angle glaucoma, and higher stressstrain index (p=0.049) than those with amyloidotic glaucoma. Biomechanically corrected intraocular pressure was significantly lower than Goldmann intraocular pressure in group with primary open-angle glaucoma (p=0.005) and control group (p=0.013), and Goldmann intraocular pressure adjusted for pachymetry in group with primary open-angle glaucoma (p=0.01). Conclusion: Eyes with amyloidotic glaucoma have more deformable corneas, while eyes with ocular hypertension have less deformable corneas. These findings may be linked to the susceptibility to glaucomatous damage and progression. There were significant differences between Goldmann applanation tonometry and biomechanically corrected intraocular ocular pressure provided by Corvis ST.
Medical Hypothesis, Discovery and Innovation in Ophthalmology, 2018
The correct estimation of Intraocular Pressure (IOP) is the most important factor in the management of various types of glaucoma. Primary congenital glaucoma is a type of glaucoma that can cause blindness in the absence of control of the IOP. In this retrospective observational study, 95 eyes, including 48 healthy eyes and 47 eyes with Primary Congenital Glaucomatous (PCG) were studied. Two groups were matched for age, gender, and Goldman Applanation Tonometry (GIOP). Corneal Hysteresis (CH), Corneal Resistance Factor (CRF), and Goldman intraocular pressure were measured by ORA (IOPg), and corneal compensated Intraocular Pressure (IOPcc) was measured for each patient using the Ocular Response Analyzer (ORA). Central Corneal Thickness (CCT) was measured by ultrasonic pachymetry. For each patient, one eye was selected randomly. Student’s t-test and analytical regression were used for statistical analysis. The two groups were matched for age (P = 0.34), gender (P = 0.47), and GIOP (P =...
PLoS ONE, 2020
Purpose To compare the corneal biomechanical parameters between pseudoexfoliation glaucoma (PXG), primary open-angle glaucoma (POAG) and healthy controls using Corvis ST. Methods A prospective, cross-sectional study was conducted which included 132 treatment-naïve eyes which underwent Corvis ST. The study cohort comprised of 44 eyes with PXG, 42 eyes with POAG and 46 healthy controls. Corneal biomechanical parameters, which included corneal velocities, length of corneal applanated surface, deformation amplitude (DA), peak distance and radius of curvature, were compared between the groups using analysis of variance models. Results The 3 groups were demographically similar. The mean IOP was 15.7 ±3 mmHg in the control group, 21.3 ±5 mmHg in the POAG group and 25.8 ±7 mmHg in the PXG group (p<0.0001). Corneal pachymetry was similar across the 3 groups. Mean DA was significantly lower (p<0.0001) in the PXG group (0.86 ±0.18 mm) compared to the POAG group (0.97 ±0.14mm) and the con...
Journal of Glaucoma, 2019
Précis: Anterior chamber depth, IOP, and thickness confounded the assessment of corneal biomechanical properties with noncontact applanation in glaucoma eyes. Compared with normal eyes, glaucoma eyes, which underwent long-term treatment or filtration surgery, had similar properties. Purpose: The purpose of this study was to evaluate corneal stiffness in primary angle-closure (PACG) and primary open-angle (POAG) glaucoma eyes that were subgrouped on the basis of the type of topical medication and filtration surgery using noncontact applanation. Methods: All eyes were retrospectively reviewed for intraocular pressure (IOP) with Corvis-ST (OCULUS Optikgerate Gmbh, Germany). Nonglaucoma (n = 140), PACG (n = 102 under medication), and POAG (n = 154 under medication) eyes were included. Corneal stiffness was calculated using deformation amplitude and a biomechanical model. Multivariate analyses were performed, which evaluated the effect of systemic conditions (diabetes and hypertension), the effect of medication (prostaglandins or beta blockers or combined), and the effect of filtration surgery (PACG: n = 23; POAG: n = 26). Age, IOP, central corneal thickness (CCT), refractive error, and anterior chamber depth (ACD) were covariates. Results: Diabetes and hypertension did not alter corneal stiffness of glaucoma eyes compared with nonglaucoma eyes (P > 0.05). Corneal stiffness of POAG and nonglaucoma eyes was similar but significantly different from the stiffness of PACG eyes (P = 0.002), irrespective of the type of topical medication. This difference was strongly correlated with ACD (P = 0.003) in addition to IOP and CCT. In eyes treated with filtration surgery, ACD (P = 0.04) again impacted the trends between nonglaucoma and glaucoma eyes. Conclusions: Medication or filtration surgery did not affect the corneal biomechanical parameters differentially from nonglaucoma eyes. However, IOP, CCT, and ACD strongly affected corneal biomechanical parameters in the same glaucoma eyes.
Investigative Ophthalmology & Visual Science, 2008
To assess the reproducibility of the ocular response analyzer (ORA) in nonoperated eyes and the impact of corneal biomechanical properties on intraocular pressure (IOP) measurements in normal and glaucomatous eyes. METHODS. In the reliability study, two independent examiners obtained repeated ORA measurements in 30 eyes. In the clinical study, the examiners analyzed ORA and IOP-Goldmann values from 220 normal and 42 glaucomatous eyes. In both studies, Goldmann-correlated IOP measurement (IOP-ORAg), corneal-compensated IOP (IOP-ORAc), corneal hysteresis (CH), and corneal resistance factor (CRF) were evaluated. IOP differences of 3 mm Hg or greater between the IOP-ORAc and IOP-ORAg were considered outcome significant. RESULTS. Intraexaminer intraclass correlation coefficients and interexaminer concordance correlation coefficients ranged from 0.78 to 0.93 and from 0.81 to 0.93, respectively, for all parameters. CH reproducibility was highest, and the IOP-ORAg readings were lowest. The median IOP was 16 mm Hg with the Goldmann tonometer, 14.5 mm Hg with IOP-ORAg (P Ͻ 0.001), and 15.7 mm Hg with IOP-ORAc (P Ͻ 0.001). Outcome-significant results were found in 77 eyes (29.38%). The IOP-ORAc, CH, and CRF were correlated with age (r ϭ 0.22, P ϭ 0.001; r ϭ Ϫ0.23, P ϭ 0.001; r ϭ Ϫ0.14, P ϭ 0.02, respectively), but not the IOP-ORAg or IOP-Goldmann. CONCLUSIONS. The ORA provides reproducible corneal biomechanical and IOP measurements in nonoperated eyes. Considering the effect of ORA, corneal biomechanical metrics produces an outcome-significant IOP adjustment in at least one quarter of glaucomatous and normal eyes undergoing noncontact tonometry. Corneal viscoelasticity (CH) and resistance (CRF) appear to decrease minimally with increasing age in healthy adults. (Invest Ophthalmol Vis Sci. 2008;49:968 -974)