Does Myopia Affect Angle Closure Prevalence.

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.