Age affects angle measurement differences among Chinese, whites, blacks

BALTIMORE — No significant difference in angle measurements was found among black, white and Chinese populations in a recent study, despite the much higher prevalence of angle closure in Chinese people. But the overall apparent similarity of the measurements between Chinese and Western populations may mask very different trends with age, the study authors suggest.

Researchers here used a new method of angle measurement — biometric gonioscopy — to measure the angles of Singaporeans of different races. They measured 15 people of each sex who were in their 40s, 50s, 60s or 70s from each of three racial groups: black, white and Chinese. The measurements were not significantly different between the groups. However, at younger ages people in the Chinese group seemed to have deeper angles than people in the white or the black group, whereas the angles of older people in the Chinese group were significantly narrower. The difference in the slope of change by age between the Chinese and both the black and white groups was statistically significant (P = .004).

The authors suggest that the more rapid decline in angle width measurements with age among Chinese people may be because of a higher prevalence of cataract or "creeping angle closure." They warn that drawing longitudinal inferences from cross-sectional studies can be problematic.

The study is published in the February issue of British Journal of Ophthalmology.