Alterations in Corneal Biomechanics and Their Correlation with Visual Field Loss in Early Primary Open-Angle Glaucoma: a case control study

Background: This study aimed to analyze corneal biomechanical properties in early-stage primary open-angle glaucoma (POAG) and identify potential biomarkers for the early diagnosis and prediction of visual field progression. Methods: Control subjects and patients with early POAG were included. Visual field defects were evaluated using a modified Advanced Glaucoma Intervention Study (AGIS) scoring method based on pattern deviation decibel maps. Only early-stage glaucoma patients (AGIS score 1–5) were included in this study. Corneal biomechanical parameters were measured using Corvis ST, including stress-strain index (SSI), applanation times (A1T, A2T), applanation velocities (A1V, A2V), highest concavity time (HC time), peak distance (PD), deformation amplitude (DA), biomechanically corrected IOP (bIOP), central corneal thickness (CCT), stiffness parameter (SP-A1), and deflection amplitudes (DefA). Group comparisons were performed using independent samples t-tests. Spearman correlation and multivariable regression analyses were employed to examine associations between corneal parameters and visual field progression. Results: A total of 134 early POAG patients and 245 healthy controls were included. Corvis ST analysis revealed significantly lower SSI in POAG patients compared to controls (0.797 ± 0.127 vs. 0.917 ± 0.132, p < 0.001). Multiple dynamic corneal response parameters—including A2T, HC time, and A2DefA—were reduced in the POAG group (p < 0.05), whereas A1DefA, HCDefA, DefArea, DAmax, and PD were elevated. AGIS scores correlated negatively with CCT, SSI, SP-A1, A1T, HC time, A2DefA, and WEM (all p < 0.05), and positively with HCDefA, DAmax, HCDefArea, and PD. Multivariate analysis identified CCT, SSI, and SP-A1 as independent predictors of AGIS scores (Regression model: AGIS score = 14.685 – 0.018 × CCT – 4.078 × SSI + 0.010 × SPA1). Conclusions: Corneal biomechanical parameters, particularly SSI, are significantly altered in early POAG and correlate with visual field loss, suggesting their potential as biomarkers for early glaucomatous impairment and disease progression monitoring.