Comparison of Anterior Segment Optical Coherence Tomography Parameters Among Vietnamese, Chinese, and Whites

Purpose: To evaluate the difference in anterior segment optical coherence tomography (AS-OCT) parameters among ethnic Vietnamese, Chinese, and whites.

Design: Cross-sectional study.

Methods: We prospectively recruited phakic nonglaucomatous participants (based on intraocular pressure < 21 mm Hg, normal optic nerve head and retinal nerve fiber, and cup-to-disc ratio < 0.6) of 3 ethnic groups-Vietnamese, Chinese, and white. AS-OCT parameters including angle (angle opening distance, trabecular-iris space area, and angle recess area), iris (iris thickness, iris area, and iris curvature [Icurv]), and anterior chamber parameters (anterior chamber depth, width [ACW], area, and lens vault [LV]) were obtained. A linear regression model with adjustment for age, sex, axial length, and pupillary diameter was used for analysis. Subgroup analysis was performed in closed- and open-angle subgroups, which were defined in eyes with gonioscopically visible posterior trabecular meshwork for less than 2 quadrants (closed) and equal to or more than 2 quadrants (open).

Results: Data were obtained from 126 Vietnamese, 124 Chinese, and 112 white participants. Mean (standard deviation) age of participants was 60.2 (11.8) years. Among overall subjects, Vietnamese had significantly smaller values in all angle and anterior chamber parameters than Chinese and white subjects (all P ≤ .001) except LV. Vietnamese had significantly higher Icurv than Chinese (B -0.065, P < .001) and white subjects (B -0.073, P < .001). In the open-angle subgroup, Vietnamese had significantly smaller angle and anterior chamber dimensions (P ≤ .001) and thicker iris (P < .001) than whites, whereas there was no significant difference in all parameters compared to Chinese except for smaller ACW in Vietnamese (P < .001). In the closed-angle subgroup, Vietnamese possessed smaller angle, smaller anterior chamber dimensions, and higher Icurv than Chinese and white subjects (P < .001). Vietnamese had significantly greater LV compared to Chinese (B -204.8, P = .001).

Conclusion: Vietnamese subjects had more of the anatomic characteristics associated with risk for angle closure, including small anterior chamber dimension, high iris curvature, and high lens vault, compared to the other 2 ethnicities.