Understanding racial differences related to angle-closure glaucoma

BETHEL, Alaska — While the reasons are still unclear, Alaskan Eskimos appear to have shallower anterior chambers than do other racial groups, according to a recent study.

Robert Wojciechowski, OD, MPH, of the Yukon-Kuskokwim Health Corp. here and colleagues noted their findings are consistent with a high reported prevalence of primary angle-closure glaucoma (ACG) among Eskimo populations. The prevalence of ACG among Eskimos in Greenland, Canada and Alaska seems to be the highest rate in the world, ranging from 2% to 4% for people 40 years of age or older.

Other racial groups, such as the Chinese, also have high rates of ACG but not shallow anterior chamber (AC) depths, the authors wrote.

“It may be that Chinese ACG prevalence is higher for some other reason, or that we simply failed to find a difference that does exist,” the authors wrote in the February issue of Ophthalmology.

This apparent rapid decline of the AC angle may be due to a cohort effect with higher prevalence of myopia that results in wider angles among younger Eskimos and Chinese, according to the study.

The authors suggested a long-term study should be conducted to distinguish between the cohort effect and a true decline in biometric parameters throughout life.

If the cohort theory proves to be true, then increasing myopia among Eskimos and Chinese is leading to deepened ACs, wider angles and lower risk of ACG among the cohort in their 40s. Dependent upon this finding, researchers believe that “the burden of this common and important cause of blindness may be reduced in East Asia in the future.”

The authors note that their study was limited to a small population (133 patients), but maintain a larger study may be impractical because of the scattered population.