Comparisons of Ocular Biometry Between Chinese and Caucasians With Anterior Segment Optical Coherence Tomography

Abstract

Purpose: : To compare anterior segment dimensions between Chinese and Caucasian subjects with narrow anterior chamber angles and to determine biometric predictors of anterior chamber angle (ACA) width using anterior segment optical coherence tomography (ASOCT).

Methods: : Thirty Chinese and thirty Caucasians with narrow angles on gonioscopy were enrolled. One eye from each subject was randomly selected for ASOCT imaging using a horizontal scan bisecting the pupil in a completely darken room. The ASOCT measurements including anterior chamber depth (ACD), ACA and iris dimensions, were compared between the two groups. General linear models were used to determine racial differences in ocular biometry after adjustment for covariates. Univariate and multivariate regression analyses were performed to evaluate the associations between ACA and other biometric measurements.

Results: : The mean age and average gonioscopy grades were 62.3±11.3 years and 0.7±0.8 in Chinese, and 59.7±13.9 years and 0.8±0.7 in Caucasians, respectively. There was no racial difference in age, gonioscopy grade, axial length, AOD, pupil diameter, and iris convexity. However, the ACD (p=0.005) and scleral spur-to-scleral spur distance (p<0.001) were smaller and the iris thickness was greater (p<0.001) in Chinese eyes. Race was significantly associated with scleral spur-to-scleral spur distance and iris thickness after adjustment for other biometric covariates. The AOD was significantly correlated with ACD and iris convexity in univariate and multivariate regression analyses.

Conclusions: : Chinese eyes had smaller anterior chamber depth (ACD), shorter scleral spur to scleral spur, and greater iris thickness than Caucasians. In addition to small ACD, increased iris convexity was found to be a significant predictor of angle narrowing.

Keywords: anterior segment • anterior chamber • imaging/image analysis: clinical