Purpose: To investigate prospectively the relation between induced changes in higher-order aberrations of the eye and changes in contrast sensitivity by conventional laser in situ keratomileusis (LASIK) for myopia.
Methods: In 200 eyes of 110 consecutive patients (mean age, 32.7 +/- 8.4 years) undergoing LASIK, ocular aberrations and contrast sensitivity function were determined before and 1 month after surgery. The amount of myopic correction was 5.2 +/- 2.8 D (range, 1.0-13.0). Ocular higher-order aberrations were measured for a 4-mm pupil using the Hartmann-Shack wavefront analyzer (KR-9000PW; Topcon, Tokyo, Japan). The root mean square (RMS) of the third- and fourth-order Zernike coefficients was used to represent coma- and spherical-like aberrations, respectively. Total higher-order aberrations were calculated as the RMS of the third- and fourth-order coefficients. Contrast sensitivity and low-contrast visual acuity were measured. From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated.
Results: LASIK significantly improved logMAR best corrected visual acuity (Wilcoxon signed-rank test, P <0.001), but significantly reduced AULCSF (P <0.001) and low-contrast visual acuity (P=0.007). Total higher-order (P <0.001), coma-like (P <0.001), and spherical-like (P <0.001) aberrations were significantly increased after LASIK. The greater the amount of achieved myopia correction was, the more the changes in contrast sensitivity function and ocular higher-order aberrations were. The induced changes in AULCSF by LASIK showed significant correlations with changes in total higher-order (Pearson r=-0.221, P=0.003), coma-like (r=-0.205, P=0.006), and spherical-like (r=-0.171, P=0.022) aberrations. The changes in logMAR low-contrast visual acuity by surgery significantly correlated with changes in total higher-order (r=0.222, P=0.003), coma-like (r=0.201, P=0.007), and spherical-like (r=0.207, P=0.005) aberrations.
Conclusions: Conventional LASIK significantly increases ocular higher-order aberrations, which compromise the postoperative contrast sensitivity function.