Abstract
Abstract: :
Purpose: Corneal refractive surgery has been shown to induce higher order aberrations, leading to reduced visual performance in some individuals. Wavefront–guided (WG) ablations have been developed with the aim of correcting higher order aberrations but studies comparing WG with conventional LASIK treatments suggest little difference in high contrast visual acuity. The purpose of this study is to determine the difference in functional visual performance for eyes undergoing myopic LASIK employing conventional, and WG treatment algorithms. Methods: Twenty eyes of ten patients were randomised to receive either conventional (preoperative MSE –4.9±1.0D) or WG LASIK (preoperative MSE –5.1±0.8D). All patients underwent the measurement of Snellen and logMAR visual acuity, Pelli Robson and refractive status, preoperatively and then at 1, 3 and 12 months postoperatively. The Contrast Acuity Assessment (CAA) test was employed to determine functional visual performance under mesopic and photopic conditions. Forward light scatter was measured using a test employing the direct compensation technique. Results There was no statistical difference in preoperative characteristics between the WG and conventional treatment groups. Both groups showed a statistically significant increase in photopic and mesopic contrast acuity thresholds at 1 month, but this reduction in visual performance was no longer significant by 3 months. Photopic and mesopic contrast acuity thresholds along with Pelli Robson scores, revealed no difference in visual performance between the WG and conventional treatment groups, at either 1 or 3 months. Unlike the CAA test, pre and postoperative Pelli Robson scores did not reveal any significant change in visual performance over time. Forward light scatter did not differ between the two groups. The overall quantity of straylight was higher at 1 month compared to preoperative values but this did not reach statistical significance. A statistically significant increase in the spread of straylight (lower scatter index value) was noted at both 1 and 3 months post–surgery. Conclusions LASIK employing either WG or conventional treatment algorithms results in a reduction in function visual performance at one month, returning to preoperative levels by 3 months (photopic and mesopic). This pilot study suggests that current WG algorithms do not currently provide any significant benefit over conventional algorithms in terms of visual performance for the average LASIK patient.
Keywords: laser • refractive surgery: comparative studies • contrast sensitivity