ASSESSMENT OF HIGH AND LOW CONTRAST VISUAL-ACUITY AFTER PHOTOREFRACTIVE KERATECTOMY FOR MYOPIA

Background. Our aim was to assess visual acuity using standardized cha rts and illumination conditions after photorefractive keratectomy. Met hods. High and low contrast visual acuity were measured on Bailey-Lovi e logarithm of the minimum angle of resolution (LogMAR) charts under h igh and low illumination conditions on 105 photorefractive keratectomy patients who had been treated with the Summit (N = 60) dr the VISX (N = 45) excimer laser. Results. Best corrected visual acuity was reduce d in the treated eye compared with the untreated control eye under ail test conditions, with the greatest differences under conditions of lo w contrast and low illumination. Reduction of acuity under low contras t and low illumination was related to small optic zone sizes and steep ablation edge profiles found in Summit-treated eyes. In the VISX-trea ted eyes, high contrast acuity was reduced in the presence of central topographical irregularities, subepithelial haze, and higher myopic co rrections. Conclusions. Testing conditions such as those described her e may be useful in quantifying vision degradation in suboptimal viewin g conditions and among patients with vague complaints.