Abstract
Abstract: :
Purpose: To investigate the alteration of higher-order aberrations following LASIK, and its effects on visual function. Methods: The subjects included in the study are 20 eyes of 17 patients who had conventional LASIK for myopia with the EC-5000 excimer laser (Nidek Inc., Japan). Wavefront sensing was performed on these eyes with the KR-9000PW (Topcon Co., Japan) for a 4 mm diameter pupil up to the fourth order. Visual function was evaluated based on high contrast visual acuity (100%ETDRS), low contrast visual acuity (10%ETDRS), Letter contrast sensitivity (LCS), and area under the log contrast sensitivity function (AULCSF) measured under full correction. Higher-order aberrations and visual function were compared between pre- and post-operative measurements. Results: Coma-like (3rd order), spherical –like (4th order) and total higher-order (total HO) aberrations after surgery were significantly higher than those before surgery, respectively (coma-like: 0.17 ± 0.05, 0.09 ± 0.04, p=0.001, Wilcoxon test, spherical-like: 0.09 ± 0.03, 0.04 ± 0.02, p=0.001, total HO:0.19 ± 0.05, 0.10 ± 0.04, p=0.001, RMS, µm).There was no significant change in 100%ETDRS (p=0.12, Wilcoxon test). However, the 10%ETDRS, LCS, and AULCSF were significantly deteriorated (p=0.001, 0.003, and 0.007). The best correlations between the changes in visual function and the changes in higher-order aberrations were obtained between LCS and spherical-like aberrations, however, there was no statistical significance (r=0.43, p=0.06). Conclusions: Although high contrast visual acuity is maintained with uneventful conventional LASIK, other contrast sensitivity tests or higher-order aberrations were affected. Since mild deterioration of contrast sensitivity in day vision caused by LASIK was not correlated well with the change in higher-order aberrations, the effects of other factors such as scattering should be investigated.
Keywords: contrast sensitivity • refractive surgery: LASIK • refractive surgery: optical quality