Ocular Monochromatic Aberrations in a Rural Chinese Adult Population

Purpose. To investigate the distribution of monochromatic aberrations in a rural Chinese adult population and the possible effect of aberrations on the development of refractive error. Methods. A total of 404 Chinese adults who grew up in rural Yongnian County, Handan City, Northern China, were included. Monochromatic aberrations of left eyes were measured using iTrace Dynamic Laser Refraction at 5.0-mm pupil size without cycloplegia. Results. Mean age of all participants was 49.9 +/- 10.5 years (range, 31 to 86 years). Mean spherical equivalent was 0.22 +/- 1.14 diopters (D) (range, -7.06 to +3.62 D). With age, the refraction demonstrated a significant hyperopic shift (r(2) = 0.25, p < 0.01). Oblique trefoil (C-3(-3)), vertical coma (C-3(-1)), horizontal coma (C-3(1)), and spherical aberration (SA) (C-4(0)) significantly differed from zero (-0.065 +/- 0.133 mu m, -0.043 +/- 0.161 mu m, + 0.070 +/- 0.115 mu m, and + 0.058 +/- 0.082 mu m, respectively). Total root mean square values of higher-order aberrations (HOAs) were 0.296 +/- 0.147 mu m, with predominant ones of coma(0.180 +/- 0.115 mu m), trefoil (0.151 +/- 0.116 mu m), and SA (0.081 +/- 0.060 mu m). Root mean square values of total HOAs, coma, trefoil, SA, and third-to seventh-order aberrations significantly increased with age (p < 0.01). Total HOAs, SA, coma, and trefoil were not significantly different between hyperopic, emmetropic, and myopic eyes after adjusting for age (p=0.26, 0.15, 0.24, and 0.28, respectively). Zernike coefficient of SA showed a significant difference between hyperopic (0.076 +/- 0.086), emmetropic (0.056 +/- 0.079), and myopic (0.028 +/- 0.088) eyes (p = 0.00). Conclusions. Ocular refraction in rural Chinese adults showed significantly hyperopic shift with age. Magnitudes of HOAs in rural Chinese adults were similar to that of other populations and significantly increased with age but showed no differences in myopic, emmetropic, and hyperopic adults. The existence of HOAs is not, in itself, sufficient to account for the myopia epidemic in China.