What question did this study set out to answer?

This study aims to determine the narrowest anterior chamber angle quadrant in primary angle-closure suspects using AS-OCT.

July 6, 2026Open Access

Quadrant-specific assessment of anterior chamber angles in primary angle-closure suspects using anterior segment-OCT: a cross-sectional observational study

Key Points

This study aims to determine the narrowest anterior chamber angle quadrant in primary angle-closure suspects using AS-OCT.
Conducted a cross-sectional study with 218 PACS subjects' right eyes.
Utilized AS-OCT to measure angles in four quadrants at specific distances from the sclera spur.
Employed multivariate linear regression to analyze associations between ocular metrics.
Significant angle width differences observed across quadrants (P<0.001 for AOD500, TISA500, TIA500).
Superior quadrant showed the narrowest angle compared to the inferior, nasal, and temporal quadrants.
Superior anterior chamber volume was positively associated with AOD500 (P<0.001), while iris thickness negatively correlated (P=0.049).

Abstract

BACKGROUND: Primary angle-closure glaucoma (PACG) is a leading cause of irreversible blindness in Asian populations. However, the topographic distribution of angle narrowing across different quadrants remains incompletely characterized in primary angle-closure suspects (PACS), and routine clinical assessments often rely solely on horizontal scans. The study aims to identify the narrowest anterior chamber angle quadrant in PACS using Anterior Segment Optical Coherence Tomography (AS-OCT). METHODS: In this community-based cross-sectional study, 218 right eyes of 218 PACS subjects were recruited. All participants underwent standardized questionnaire surveys and ophthalmic examinations. AS-OCT parameters including angle opening distance (AOD), trabecular iris space area (TISA) and trabecular iris angle (TIA) were measured at 500 μm from the sclera spur (SS) in the superior, inferior, nasal and temporal quadrants. As iridotrabecular contact (ITC) in more than one quadrant precluded identification of the narrowest quadrant, only narrow-angle eyes (ITC in < 2 quadrants) were included in the analysis. Quadrant-wise comparisons and multivariate linear regression analyses were performed. RESULTS: Significant differences in angle width were observed across all four quadrants (P<0.001 for AOD500, TISA500, and TIA500). The superior quadrant exhibited the narrowest angle, followed by the inferior, nasal, and temporal quadrants in narrow-angle eyes. Multivariate linear regression analysis revealed that superior anterior chamber volume (ACV- superior)was positively associated (P<0.001), while superior iris thickness at 750 μm (IT750-superior) was negatively associated (P = 0.049) to superior AOD500. CONCLUSION: The superior quadrant is consistently the narrowest in PACS eyes, highlighting the necessity of including vertical cross-sectional scans in routine AS-OCT examination protocols for this population. TRIAL REGISTRATION: The study was registered in the Chinese Clinical Trial Registry on September 4th, 2020 (Registration Number: ChiCTR2000037944).

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