Purpose: To conduct a simulation study to estimate the prevalence of occludable angle (OA), a surrogate for primary angle closure glaucoma (PACG), with the increased rate of myopia in the Chinese population.
Methods: People with phakic eyes in Liwan Eye Study were included as the study sample. Anterior chamber depth (ACD) was measured before dilation by A-mode ultrasound and OA was evaluated with static gonioscopy. Random sampling was used to generate 50 cohorts with sample size of 200 for each of myopic rates 10%, 20%, 40%, 50%, and 135 for myopic rate 60%, according to the multinomial distribution. The mean ACD and OA rates of each cohort were calculated. Logistic function model of nonlinear least-squares estimation was used to predict the prevalence of OA.
Results: Data of the right eyes from 1160 subjects were qualified for analysis. The mean age was 64.2 ± 9.5 years, with 43% being male. The prevalence of myopia and OA was 32.5% (95% confidence interval [CI], 29.8%-35.3%) and 10.3% (95% CI, 8.7%-12.2%), respectively. The mean ACD in the sampling cohorts increased from 2.68 mm to 2.74 mm when the prevalence of myopia increased from 10% to 60%. The projected prevalence of OA in the cohorts with myopia prevalence of 10%, 20%, 40%, 50%, and 60% was 11.1% (95% CI, 10.5%-11.8%), 10.7% (95% CI, 10.1%-11.4%), 9.9% (95% CI, 9.3%-10.5%), 9.3% (95% CI, 8.8%-9.9%), and 9.6% (95% CI, 8.9-10.3%), respectively.
Conclusions: The increasing prevalence of myopia has minimal impact on the prevalence of OA.