Anterior Segment Optical Coherence Tomography Characteristics in an Asian Population

Purpose: To quantify the angle characteristics in an Indian population, and determine the prevalence of eyes at risk of angle closure. Materials and Methods: This population-based cohort study was carried out to evaluate individuals, 40 to 59 years of age, clinically. The individuals underwent anterior segment optical coherence tomography of their right eyes in the horizontal meridian, using the enhanced protocol. Results: The mean scleral spur angle for the population was 24.2 +/- 10.2 degrees, and a manually measured angle recess was 23.2 +/- 10.2 degrees, with a kappa value of agreement of 0.78, 85.7%. An angle of <20 degrees was seen in 154 eyes, 38.7%, 20 to 30 degrees in 154 eyes, 38.7%, and >30 degrees in 90 eyes, 22.6%. An anterior chamber angle of <20 degrees was significantly associated with age, sex, and a steep iris configuration. The scleral spur angle and the manually recorded anterior chamber angle recess correlated very well with all angle ultrasound biomicroscopy parameters, but showed the highest receiver operating characteristic curve with trabecular iris space area 500, r = 0.989 and angle opening distance 750, r = 0.943. On multivariate analysis, there was a significant correlation with trabecular iris space area, angle opening distance, and height. Conclusions: Of individuals, 38.7%, 40 to 60 years of age, were found to have an anterior chamber angle of <20 degrees, reflecting the high prevalence of primary angle closure and primary angle closure glaucoma in India.