Ocular higher-order aberrations in individuals screened for refractive surgery

To explore the distribution of ocular higher-order aberrations (HOAs, 3rd to 6th orders) in the population, evaluate the symmetry of ocular aberrations between right and left eyes in each subject using a Hartmann-Shack wavefront sensor, and study the differences in aberration as a function of age.

Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA.

Ocular HOAs were examined across a 6.0 mm pupil in 532 eyes of 306 subjects (mean age 41 years +/- 10 [SD] [range 20 to 71 years]; mean WaveScan spherical equivalent -3.39 +/- 2.84 diopters [D] [range -11.56 to 7.60 D]) using the WaveScan system (Visx, Inc.). Zernike coefficients and root-mean-square (RMS) values of HOAs, spherical aberration (SA, Z(4)(0) and Z(6)(0)), and coma (Z(3)(-1), Z(3)(1), Z(5)(-1), and Z(5)(1)) were analyzed. Correlation analysis was performed to assess the association between ocular HOAs and age and investigate the aberration symmetry between right and left eyes.

For individual terms, the highest mean absolute values were for 4th-order SA (Z(4)(0)), 3rd-order coma, and trefoil terms. The mean RMS values of HOA, SA, and coma were 0.305 +/- 0.095 microm, 0.128 +/- 0.074 microm, and 0.170 +/- 0.089 microm, respectively. Moderate to high correlations were found between the right and left eyes for HOA, SA, and coma (Pearson correlation coefficient = 0.601, 0.776, and 0.511, respectively; all P<.001). Thirteen of the 22 Zernike terms (59%) were significantly correlated across eyes (Bonferroni correction, P'<.05/22). Higher-order aberrations, SA, and coma were weakly correlated with age (r = 0.317, 0.273, and 0.176, respectively; all P<.002).

Wavefront aberrations varied widely among subjects and increased slightly with age. A moderate to high degree of mirror symmetry existed between right and left eyes.