Ethnic differences in higher-order aberrations: Spherical aberration in the South East Asian Chinese eye

PURPOSE: To determine the distribution of higher-order corneal and ocular aberrations in a healthy refractive surgery population. SETTING: Island Hospital, Penang, Malaysia. METHODS: In this prospective observational study, 1 eye of ethnic Chinese refractive surgery patients was evaluated with an Orbscan II corneal topographer and a Zywave Hartmann-Shack aberrometer with a 6.0 mm pupil. Height data were analyzed to derive the higher-order aberrations (HOAs) from the 3rd to 5th Zernike order. RESULTS: The mean spherical equivalent in the 70 eyes evaluated was -6.46 diopters +/- 3.10 (SD). The mean total corneal HOA was 0.574 +/- 0.218 mu m (range 0.269 to 1.249 mu m) and the mean total ocular HOA, 0.525 +/- 0.354 mu m (range 0.138 to 2.145 mu m). There was no statistically significant correlation with age. The mean 3rd-order ocular aberration was 0.399 +/- 0.287 mu m; the mean 4th-order, 0.297 +/- 0.223 mu m; and the mean 5th-order, 0.108 +/- 0.101 mu m. Corneal spherical aberration was greater than ocular spherical aberration (mean 0.312 +/- 0.114 mu m versus 0.200 +/- 0.170 mu m). Multilinear regression showed that the only dependent that predicted ocular spherical aberration was anterior corneal asphericity (r(2) = 0.227, F = 17.95, P<.001). CONCLUSION: Corneal and ocular aberrations in South East Asian Chinese eyes were significantly greater than that reported in other populations. Population differences in wavefront errors were significant, and this should be noted in patient management.