title: Photorefractive keratectomy versus laser in situ keratomileusis: comparison of optical side effects. Summit PRK-LASIK Study Group.
abstract: OBJECTIVE
  This report presents patient-reported optical symptoms after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).
  
  
  METHODS
  Preoperative and postoperative patient surveys in a prospective, multicenter, randomized clinical trial.
  
  
  METHODS
  Two hundred twenty eyes of 220 patients entered the study; 105 were randomized to PRK and 115 were randomized to LASIK.
  
  
  METHODS
  All patients received a one-pass, multizone excimer laser ablation as part of either a PRK or LASIK procedure. Attempted corrections ranged from 6.00 to 15.00 diopters (D).
  
  
  METHODS
  Glare, halo, and monocular diplopia symptoms as reported by patients on questionnaires before surgery and at the 6-month follow-up. Comparison was made between symptoms when using optical correction before surgery and symptoms without correction after surgery.
  
  
  RESULTS
  For both the PRK and LASIK groups analyzed individually, the difference in average glare index before surgery and after surgery was not statistically significant (P = 0.54 for PRK; P = 0.15 for LASIK; t test). Twenty-four PRK patients (41.4%) reported worsening of glare symptoms from baseline compared with 11 LASIK patients (21.6%); however, the difference between the two groups was not statistically significant (P = 0.086, chi-square test). Within the PRK group, the difference in average halo index before and after surgery was statistically significant (P = 0.0003, t test); in the LASIK group, it was not statistically significant (P = 0.1 1, 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 statistically significant (P = 0.086, chi-square test). For both the PRK and LASIK groups, the difference in average diplopia index before and after surgery was 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 difference was not statistically significant (P = 0.39, chi-square test). When changes 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 greater likelihood of demonstrating an increase in symptoms compared with the LASIK group (P = 0.048, chi-square test).
  
  
  CONCLUSIONS
  Optical sequelae of glare, halo, and monocular diplopia may occur in some patients after either both PRK or LASIK for moderate to high myopia; in contradistinction, many other patients' preoperative symptoms improve after surgery. On average, PRK patients show an increase in halo and diplopia symptoms, but not glare, after surgery, and LASIK patients show an increase in diplopia, but not glare and halo symptoms. There is a suggestion of a somewhat lesser tendency toward postoperative optical symptoms in LASIK compared with PRK treated eyes.
authors.affiliation: Department of Ophthalmology, UMDNJ-New Jersey Medical School, Newark 07103, USA. phersh@vision-institute.com
authors.forename: P S
authors.initials: PS
authors.lastname: Hersh
authors.forename: R F
authors.initials: RF
authors.lastname: Steinert
authors.forename: S F
authors.initials: SF
authors.lastname: Brint
mesh_terms: D000328:Adult; D003315:Cornea / Q000601:surgery*; D004172:Diplopia / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D019466:Glare; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000009:adverse effects*; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D014792:Visual Acuity