Central Corneal Thickness in Northwestern American Indians/Alaskan Natives and Comparison with White and African-American Persons

PURPOSE: To determine the demographic factors associated with central corneal thickness (CCT) in Northwestern American Indians/Alaskan Natives (AI/ANs) and to compare these CCT measurements with those of White and African-American persons. DESIGN: Cross-sectional comparative, observational study. METHODS: We performed ultrasonic pachymetry (DGH 500 Pachette; DGH Technologies, Exton, Pennsylvania, USA) on a random sample of AI/AN subjects from three randomly selected AI/AN tribes in the North,vest United States (n = 429). Pachymetry also was performed on a convenience sample of White (n = 46) and African-American (n = 33) persons. Our main outcome measure was the average of right and left eye CCT. RESULTS: Average AI/AN CCT was 554.8 +/- 33.9 mu m. AI/AN CCT was found to be thicker than that of African Americans (528.5 +/- 33.2 mu m) but similar to that of White persons (551.9 +/- 28.3 mu m). CCT was greater in AI/AN females than in AI/AN males (557.6 +/- 33.3 mu m vs 550.1 +/- 34.55 mu m; P = .03). We found no difference in CCT based on percent AI/AN heritage, age, and keratometry readings. We found no significant differences in mean CCT between AI/ANs with glaucoma (556.2 mu m) and those who did not have glaucoma (556.6 mu m). CONCLUSIONS: CCT measurements for the Northwest AI/AN population are similar to those of White persons but thicker than those of African American persons. Although glaucoma is common in AI/ANs, we did not find an association with thin CCT. We need future studies to explore the risk factors for glaucoma in AI/ANs. (Am J Ophthalmol 2008;146:747-751. (C) 2008 by Elsevier Inc. All rights reserved.)