Abstract
Purpose: :
To describe novel computer-assisted measurements of anterior chamber area (ACA) and anterior chamber volume (ACV) based on anterior-segment optical coherence tomography (AS-OCT) images, and to investigate the association of these measurements with the presence of narrow angles in a Singapore population.
Methods: :
2047 subjects aged 50-years and over without ophthalmic symptoms recruited from a community polyclinic underwent gonioscopy, anterior chamber depth and axial length measurement (IOL Master, Zeiss) and AS-OCT (Visante, Carl Zeiss Meditec, Dublin, CA). Customized computer software (Zhongshan Angle Assessment Program, Guangzhou, China) was used to measure ACA and ACV. An eye was considered to have narrow angles if the posterior pigmented trabecular meshwork was not visible for≥180° on non-indentation gonioscopy with the eye in the primary position.
Results: :
467 subjects were excluded mainly due to poor localization of the sclera spur, leaving 1465 subjects for analysis. Of these, 315 subjects (21.5%) had narrow angles. The mean ACA (15.64 vs 20.95 mm2, P<0.001) and ACV (97.5 vs 141.3 mm3, P<0.001) were significantly smaller in eyes with narrow angles compared to those without narrow angles. After adjusting for age, gender, anterior chamber depth, axial length, and pupil size, smaller ACA (odds ratio [OR] 52.1, 95% confidence interval [CI], 19.5-139.5) and ACV (OR 30.7, 95% CI, 13.0-72.5) were significantly associated with narrow angles, comparing lowest quartile to the highest two quartiles for each parameter respectively.
Conclusions: :
ACA and ACV are independently associated with the presence of narrow angles in Asians. These data suggest that quantitatively measured anterior chamber area and volume are novel risk factors for angle closure.
Keywords: anterior chamber • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)