Photorefractive keratectomy versus laser in situ keratomileusis - Comparison of optical side effects

Objective: This report presents patient-reported optical symptoms after pho torefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Design: Preoperative and postoperative patient surveys in a prospective, mu lticenter, randomized clinical trial. Participants: Two hundred twenty eyes of 220 patients entered the study; 10 5 were randomized to PRK and 115 were randomized to LASIK. Intervention: All patients received a one-pass, multizone excimer laser abl ation as part of either a PRK or LASIK procedure. Attempted corrections ran ged from 6.00 to 15.00 diopters ID). Main Outcome Measures: Glare, halo, and monocular diplopia symptoms as repo rted by patients on questionnaires before surgery and at the 6-month follow -up. Comparison was made between symptoms when using optical correction bef ore surgery and symptoms without correction after surgery. Results: For both the PRK and LASIK groups analyzed individually, the diffe rence in average glare index before surgery and after surgery was not stati stically significant IP = 0.54 for PRK; P = 0.15 for LASIK; t test). Twenty -four PRK patients (41.4%) reported worsening of glare symptoms from baseli ne compared with 11 LASIK patients (21.6%); however, the difference between the two groups was not statistically significant (P = 0.086, chi-square te st). Within the PRK group, the difference in average halo index before and after surgery was statistically significant (P = 0.0003, t test); in the LA SIK group, it was not statistically significant (P = 0.11, t test). Thirty- four PRK patients (58.6%) reported worsening of halo symptoms from baseline compared with 26 LASIK patients (50.0%); this difference was not statistic ally significant (P = 0.086, chi-square test). For both the PRK and LASIK g roups, the difference in average diplopia index before and after surgery wa s statistically significant (P ( 0.0001 for PRK; 0.047 for LASIK; t test). Twenty-six PRK patients (44.8%) reported a worsening of monocular diplopia symptoms from baseline compared with 19 LASIK patients (35.8%); this differ ence was not statistically significant IP = 0.39, chi-square test). When ch anges in glare and halo from before surgery to after surgery were pooled as a glare-halo index, however, the PRK group did show a significantly greate r likelihood of demonstrating an increase in symptoms compared with the LAS IK group (P = 0.048, chi-square test). Conclusions: Optical sequelae of glare, halo, and monocular diplopia may oc cur in some patients after either both PRK or LASIK for moderate to high my opia; in contradistinction, many other patients' preoperative symptoms impr ove after surgery. On average, PRK patients show an increase in halo and di plopia symptoms, but not glare, after surgery, and LASIK patients show an i ncrease in diplopia, but not glare and halo symptoms. There is a suggestion of a somewhat lesser tendency toward postoperative optical symptoms in LAS IK compared with PRK treated eyes. (C) 2000 by the American Academy of Opht halmology.