Comparison of corneal biomechanics among primary open-angle glaucoma with normal tension or hypertension and controls

Abstract

Background:Normal tension glaucoma (NTG) is a less pressure-dependent type of glaucoma with characteristic optic neuropathy. Recently, the biomechanical mechanism has been thought to account for glaucomatous optic neuropathy to some degree. We intended to compare dynamic corneal response parameters (DCRs) among patients with primary open-angle glaucoma with normal tension or hypertension and controls. The correlations between DCRs and known risk factors for glaucoma were also analyzed.Methods:In this cross-sectional study, 49 NTG subjects, 45 hypertension glaucoma (HTG) subjects, and 50 control subjects were enrolled. We compared the differences in DCRs using corneal visualization Scheimpflug technology among the NTG, HTG, and control groups. We also analyzed the correlations between DCRs and known risk factors for glaucoma (eg, central corneal thickness [CCT], intraocular pressure [IOP], etc).Results:The maximum inverse concave radius (NTG: 0.18 [0.17, 0.20] mm−1; control: 0.17 [0.16, 0.18] mm−1; P = 0.033), deformation amplitude ratio of 2 mm (DAR 2 mm, NTG: 4.87 [4.33, 5.39]; control: 4.37 [4.07, 4.88]; P < 0.001), and DAR 1 mm (NTG: 1.62 [1.58, 1.65]; control: 1.58 [1.54, 1.61]; P < 0.001) were significantly higher in NTG than in the controls. The integrated radius (IR, NTG: 8.40 ± 1.07 mm−1; HTG: 7.64 ± 1.31 mm−1; P = 0.026) and DAR 2 mm (NTG: 4.87 [4.33, 5.39]; HTG: 4.44 [4.12, 5.02]; P < 0.007) were significantly higher, whereas the stiffness parameter at the first applanation (SP-A1, NTG: 91.23 [77.45, 107.45]; HTG: 102.36 [85.77, 125.12]; P = 0.007) was lower in NTG than in HTG. There were no significant differences in the DCRs between HTG and control groups (P > 0.05). In the univariate and multivariate analyses, some of the DCRs, such as IR, were negatively correlated with CCT and IOP, whereas SP-A1 was positively correlated with CCT and IOP.Conclusions:The cornea was more deformable in NTG than in HTG or controls. There were no significant differences in corneal deformability between HTG and controls. The cornea was more deformable with the thinner cornea and lower IOP.

The role of corneal biomechanics in visual field progression of primary open-angle glaucoma with ocular normotension or hypertension: a prospective longitude study

“…We found that for HTG, there was no significant difference in DCRs between the groups with or without visual field progression. The results were consistent with previous observations that corneal biomechanical parameters were not significantly different between the HTG and normal groups ( Wei et al, 2021 ). Our results indicated that VF progression in the HTG group with a 30% decrease in IOP compared with the baseline IOP was not related to corneal biomechanics.…”

“…The results indicated that the progressive group had a greater corneal depression depth, displacement area and flattening length at the first applanation than the nonprogressive group, which might indicate that the progressive group had a more deformable cornea. As previous studies ( Li et al, 2017 ; Wei et al, 2021 ; Wu et al, 2022 ) indicated that cornea biomechanics were related with age, sex, CCT, AL, IOP, and glaucoma severity, these factors were adjusted in the analysis. In baseline comparisons, MD in the progressive group (−10.33 dB) was lower than that of the nonprogressive group (MD: −5.57 dB), while the difference was not significant ( p = 0.254).…”

“…Another study that did not distinguish NTG from HTG obtained opposite results in that thin and hard corneas were more likely to progress ( Qassim et al, 2021 ). Considering the differences in pathogenesis between NTG and HTG ( Wei et al, 2021 ), the classification of NTG and HTG in the analysis of POAG corneal biomechanics is vital. Besides, the parameters used in this study were different and acquired with the whole eye retreat movement eliminated ( Wu et al, 2022 ), which made the results more accurate.…”

Correlations among Corneal Biomechanical Parameters, Stiffness, and Thickness Measured Using Corvis ST and Pentacam in Patients with Ocular Hypertension

“…In this study, SSI and SP-A1 showed corneal stiffness changes and decreased significantly after pharmacotherapy. Consistent with the findings of previous research, A1L, A2L, HCT, and HCR infrequently showed no significant changes after long-term pharmacotherapy or at an early stage after surgery [ 2 , 8 , 21 , 22 ].…”

Biomechanical analysis of ocular diseases and its in vitro study methods

“…Biomechanical mechanisms are thought to partly explain glaucoma optic neuropathy, Wei et al [ 21 ] analyzed dynamic corneal response parameters by comparing normal-tension glaucoma subjects, hypertension glaucoma subjects, and control subjects. Results showed that the corneal deformation of normal-tension glaucoma was more pronounced than in hypertension glaucoma or the control group, people with hypertension glaucoma showed no significant difference in corneal deformation ability compared with the control group.…”