More crowded anterior segment likely in Chinese eyes

San Francisco-Ethnic differences in anterior chamber angle anatomy exist and may explain the increased risk for angle-closure glaucoma among Chinese, said Shan C. Lin, MD, professor of ophthalmology and co-director of the glaucoma service, University of California San Francisco School of Medicine.

To try to understand ethnicity-related variations in angle-closure glaucoma risk, Dr. Lin and colleagues undertook prospective evaluations of anterior segment biometry features in four gender- and age-matched cohorts representing a southern mainland Chinese population, a northern mainland Chinese population, a Chinese American population, and a Caucasian American population. As there were no significant differences in the anterior segment parameters between the Chinese populations from America and China, the data for all Chinese eyes were pooled for comparison with the Caucasians.

The results showed that relative to the Caucasians, the Chinese eyes had significantly smaller anterior chamber depth, corneal arc depth, and anterior chamber width, even after adjustment for refractive status and axial length. Anterior chamber area and volume were also significantly lower in the Chinese eyes than in the Caucasians.

In addition, iris thickness near the iris root, as measured in dark conditions, was significantly greater in the Chinese eyes. Iris area was also significantly greater in the Chinese eyes, and the dynamic change in iris root thickness closest to the angle was also significantly greater in Chinese eyes.

Significant differences in the angle itself were also identified with the deep angle recess being significantly smaller in the Chinese eyes after adjusting for differences in axial length and refractive error.

“The bottom line is that Chinese eyes have a more crowded anterior segment,” Dr. Lin concluded.

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