Time–course of changes in contrast sensitivity function and higher–order aberration after laser in situ keratomileusis

Abstract

Abstract: : Purpose: It has been reported that laser in situ keratomileusis (LASIK) significantly increases higher–order aberrations of the eye. Contrast sensitivity is also compromised by LASIK but reportedly recovers to the preoperative level by 6 to 12 months after surgery. There have been no reports, however, on the long–term relation between contrast sensitivity and ocular higher–order aberration after LASIK. Methods: Contrast sensitivity function and ocular aberrations were determined before and 1, 6, 12 months after LASIK in 100 eyes of 51 patients (mean age 32.3 ± 9.0 years old). Mean preoperative refractive error was –5.22 ± 2.53 D (range, –1.0 to –13.5 D). Low contrast visual acuity (1000LanC10%), area under the log contrast sensitivity function (AULCSF, 1000E), and letter contrast sensitivity (1000LV) were measured with Vector Vision CSV–1000 charts. Higher–order aberrations of the eye were measured with a Hartmann–Shack wavefront aberrometer (Topcon KR–9000PW) for a central 4–mm diameter. Results: LASIK significantly improved best spectacle–corrected visual acuity (p<0.01, paired t–test). AULCSF decreased by LASIK, and values 1 and 6 months after surgery were significantly lower than the preoperative AULCSF (p<0.01). LASIK significantly reduced low contrast visual acuity 1 month after surgery (p<0.05, paired t–test), which returned to the preoperative level by 3 months postoperatively. LASIK induced significant increases in ocular higher order aberrations (p<0.01), which persisted throughout the on–year study period. On each postoperative point, increases in higher–order aberration significantly correlated with reductions in contrast sensitivity function (p<0.05). Conclusions: After LASIK, increases in ocular higher–order aberration were persistent, while reductions in contrast sensitivity function were transient with values returning to the preoperative level by 12 months.

Keywords: contrast sensitivity • refractive surgery: LASIK • refractive surgery: optical quality