Dynamic Changes in Anterior Chamber Angle on Anterior Segment OCT Under Photopic and Scotopic Conditions
Year: 2025
Type: article
Study design: Observational Study
Abstract: Background: Configuration of an anterior chamber angle is dynamic and varies with physiologic pupil dilation. Non-contact quantitative evaluation of these changes can be done with anterior segment optical coherence tomography (AS-OCT). Purpose; To compare parameters of anterior chamber angles in sub-irradiated conditions with photopic and scotopic and to identify other variables related to the decreasing of angle in scotopic environment. Techniques: This prospective paired-observation study involved 120 phakic adults, 60 primary angle-closure suspects (PACS) and 60 open-angle controls. S swept-source AS-OCT was performed on the eye of a single participant after standard photopic and scotopic adaptation. Angle-opening distance 500 ml (AOD500), area of trabecular-iris space 500 ml (TISA500), trabecular-iris angle (TIA500), curvature of iris, anterior chamber volume (ACV), pupil diameter, lens vault and anterior chamber depth were examined. Paired tests, mixed-effects models, correlation and multivariable linear regression were performed. Results: Mean pupil diameter increased from 3.09±0.43 to 5.29±0.58 mm (p<0.001). AOD500 decreased from 0.317±0.132 to 0.241±0.152 mm, while TISA500 and TIA500 also decreased (all p<0.001). Angle narrowing was greater in PACS than controls (mean ΔAOD500 0.100 vs 0.053 mm; p<0.001). Pupil dilation correlated with ΔAOD500 (r=0.38, p<0.001). Significant independent predictors of more narrowing against nominal odds of PACS status were the older age and higher pupil dilation. Conclusion: It demonstrates that scotopic light resulted in minimal angle narrowing in PACS eye, indicating the need to standardize light in AS-OCT evaluation.
Language: English
Subfield: Ophthalmology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
OpenAlex ID: W7214749672