Corneal Edema and Associated Visual Quality Following Lasek: A Preliminary Study

Abstract

Abstract: : Purpose:To evaluate the effect of corneal edema on visual quality after laser epithelial keratomileusis (LASEK). Methods: Fifteen human subjects (30 eyes) with myopia ranging from –3.50D to –7.00D were treated by routine LASEK. Eyes were evaluated for 9 months post–surgically, including evaluation of the epithelial flap, corneal responses and visual acuity (LogMAR) twice during the first week and once a week thereafter. Contrast sensitivity and wavefront aberrations were measured at 2 and 12 weeks and 9 months. Results: LASEK was successfully performed in all eyes with no obvious post–surgical discomfort. Moderate edema at the subepithelial cornea occurred in all eyes immediately after surgery and this substantially subsided in 70% of eyes (n = 21) at 3 weeks and 30% of eyes (n = 9) at 5 weeks. Visual quality was compromised depending on the severity of edema in all eyes after surgery. This included a significant reduction in best–corrected visual acuity (BCVA) and contrast sensitivity function (CSF) with an increase in wavefront aberrations (p < 0.01 or 0.05, compared to pre–surgical levels). The reduction in CSF was mainly at high frequencies and the increase in wavefront aberrations was most obvious at coma aberrations. All visual quality components recovered towards pre–surgical levels as edema subsided. Complete recovery required approximately 3 months for BCVA, CSF and non–coma aberrations in most of the eyes following LASEK, with recovery of coma aberrations taking longer. Conclusions: Subepithelial edema is the major corneal response which compromised visual quality after LASEK. Recovery of the visual quality depends at least in part to the length of time needed for corneal edema to subside, indicating the importance of active treatment for the edema after LASEK.

Keywords: cornea: epithelium • laser • visual acuity