Spectral-domain OCT evaluation of anterior sclera and aqueous outflow structures in POAG, ocular hypertension, and healthy eyes

Eye (Lond). 2026 May 13. doi: 10.1038/s41433-026-04526-w. Online ahead of print.

ABSTRACT

PURPOSE: To compare anterior scleral thickness (AST) and aqueous outflow structure metrics Schlemm's canal area (SCA), trabecular meshwork thickness (TMT), and scleral spur length (SSL) among primary open-angle glaucoma (POAG), ocular hypertension (OHT), and healthy eyes using spectral-domain OCT (SD-OCT), and to evaluate their inter-relationships.

METHODS: In this prospective study, we included 126 participants (56 POAG, 24 OHT, 46 controls) from a tertiary glaucoma clinic (January-May 2025). One eye per subject was analysed. SD-OCT (REVO 60, Optopol, Poland) was used to obtain horizontal anterior-segment scans in nasal and temporal quadrants. AST was measured at 0-3 mm from the scleral spur (AST0-AST3); SCA, TMT, and SSL were quantified on exported images using Fiji/ImageJ with pixel-to-micron calibration. Group comparisons employed ANOVA/Kruskal-Wallis with post-hoc tests. Correlations and multiple linear regression assessed determinants of nasal AST0. Inter-observer repeatability was evaluated with ICC.

RESULTS: Mean age was 67.9 ± 10.0 (POAG), 62.7 ± 10.4 (OHT), and 62.9 ± 6.6 years (controls). AST0 was significantly lower in POAG and OHT compared with controls in both nasal and temporal quadrants (all p < 0.001). For AST3, temporal values were lower in POAG and OHT compared with controls (p < 0.001), while nasal AST3 showed no significant group difference. SCA and SSL were significantly lower in POAG and OHT compared with controls in both quadrants (all p < 0.001). TMT tended to be lower in patient groups but often did not reach significance. In multivariable analysis, nasal SCA and nasal SSL were independent positive predictors of nasal AST0 (both p < 0.001; model R² = 0.356). Inter-observer ICCs ranged 0.78-0.93 (highest for nasal SCA = 0.93), indicating good repeatability.

CONCLUSIONS: POAG and OHT are characterised by a thinner anterior sclera and smaller Schlemm's canal area and scleral spur length compared with controls. The independent association of SCA and SSL with AST supports a biomechanical coupling between the perilimbal sclera and outflow structures. These metrics warrant further longitudinal study for diagnostic/prognostic utility.

PMID:42129342 | DOI:10.1038/s41433-026-04526-w