Inter-eye comparison of corneal stiffness parameters in primary open-angle glaucoma patients with unilateral damage

To investigate inter-eye differences in corneal biomechanical properties as assessed by Corvis ST among primary open-angle glaucoma (POAG) patients with unilateral damage.

prospective cross-sectional study.

This study included 240 eyes from 120 treatment-naïve patients with POAG, of which 60 were classified as normal-tension glaucoma (NTG) and 60 as high-tension glaucoma (HTG). Paired eyes were categorized into glaucomatous eyes and clinically unaffected fellow eyes according to ophthalmic examination. Ocular parameters, including corneal biomechanical properties, were compared between paired eyes within each group (POAG group, NTG and HTG subgroup). The generalized estimation equation (GEE) models with a binary logistic link were employed to examine the association between ocular parameters and the presence of glaucoma.

Eyes with POAG had significantly higher biomechanically corrected intraocular pressure (bIOP; p = 0.007), more negative spherical equivalent (SE; p = 0.018), longer axial length (AL; p = 0.006), and thinner central corneal thickness (CCT; p = 0.007) than unaffected fellow eyes. Binocular comparison results differed across subgroups. NTG eyes had significantly thinner CCT (p = 0.015) and lower stiffness parameter at first applanation (SP-A1; p = 0.013) than unaffected fellow eyes. In contrast, HTG eyes showed significantly higher bIOP (p = 0.002), more negative SE (p = 0.047), and longer AL (p = 0.009) compared to controls. Multivariable GEE analysis demonstrated that higher baseline bIOP was significantly associated with the presence of both POAG (odds ratio, 1.111; p = 0.009) and HTG (odds ratio, 1.225; p = 0.002). In the NTG subgroup, lower SP-A1 was the only factor significantly correlated with the presence of glaucoma (odds ratio, 0.985; p = 0.035).

Increased baseline bIOP was correlated with unilateral glaucomatous damage in patients with POAG and HTG. However, a lower corneal stiffness parameter was associated with glaucomatous eyes in NTG. This finding suggests that eyes with a more deformable cornea are vulnerable to glaucomatous damage, even when the IOP is within the normal range.