Subgrouping of Angle Closure Patients based on Anterior Segment Optical Coherence Tomography Parameters

Abstract

Purpose: To identify subgroups of primary angle closure patients based on anterior segment optical coherence tomography (ASOCT) and biometric parameters.

Methods: We evaluated 315 subjects with primary angle closure, who underwent gonioscopy and ASOCT (Carl Zeiss Meditec, Dublin, CA). Customized software (Zhongshan Angle Assessment Program, Guangzhou, China) was used to measure ASOCT parameters. Agglomerative hierarchical clustering method was first utilized to determine the optimum number of parameters to be included in the determination of subgroups. The best number of subgroups were then determined using the Akaike Information Criterion (AIC) and Gaussian Mixture Model (GMM) method.

Results: The mean age of angle closure subjects was 64.8 years, and 64.4% were female. Using the hierarchical clustering method, the optimal number of parameters was four, namely iris area (IArea), anterior chamber depth (ACD), anterior chamber width (ACW), and lens vault (LV), each chosen from a different parameter cluster. Using the GMM method, the optimal number of subgroups as given by AIC was three. Subgroup 1 was characterised by a large IArea and a small ACW; subgroup 2 by a large LV and a shallow ACD; while the features in subgroup 3 included elements of both subgroups 1 and 2. The results were replicated in a second independent group of 165 hospital-based subjects with angle closure.

Conclusions: Clustering analysis identified three distinct subgroups of angle closure subjects based on ASOCT and biometric parameters. These findings may be relevant for understanding angle closure pathogenesis and management.

Keywords: 421 anterior segment • 550 imaging/image analysis: clinical • 464 clinical (human) or epidemiologic studies: risk factor assessment