title: Results of bilateral photorefractive keratectomy.
abstract: OBJECTIVE
  To study the refraction and potential risks of bilateral photorefractive keratectomy for myopia.
  
  
  METHODS
  Retrospective, noncomparative case series.
  
  
  METHODS
  Four hundred eighteen consecutive patients (836 eyes) with myopia from -18 to -0.50 diopters (D) had bilateral simultaneous refractive surgery.
  
  
  METHODS
  Refractive surgery was performed with the Nidek EC-5000 slit-scanning excimer laser (Nidek Co., Tokyo, Japan).
  
  
  METHODS
  Manifest refraction, Snellen best spectacle-corrected visual acuity (BSCVA) and uncorrected visual acuity, haze, and halos were evaluated for 12 months after surgery. Both eyes of each patient were examined at the same follow-up after initial treatment.
  
  
  RESULTS
  At 12 months after surgery, 95% of eyes were within +/- 1D of emmetropia, and 0.4% of patients had residual anisometropia more than 2 D. Thirty-three eyes (3.9%) were retreated, whereas 5 patients (1.2%) had retreatments in both eyes. Odds ratios between unilateral versus bilateral postoperative events were evaluated for the retreatments (1:0.22; P = 0.001), undercorrections more than 1 D (1:0.17; P < 0.0001), overcorrections more than 1 D (1:0.23; P < 0.0001), loss of 1 line of BSCVA (1:0.44; P < or = 0.002), and loss of 2 lines of BSCVA (1:0.18; P = 0.013). At 12 months after surgery, one eye with a loss of 2 lines of BSCVA was treated for haze more than 1; the fellow eye had haze 0.75. No patient had bilateral haze more than 1. At 12 months after surgery, no patient lost 2 lines of BSCVA in both eyes. There was a higher incidence of halos in both eyes rather than in one eye only (odds ratio: 4.17; P < 0.0001). No postoperative infections occurred.
  
  
  CONCLUSIONS
  Bilateral events occurred approximately 2.5 to 4 times less often than unilateral events, except for the incidence of halos. The calculated odds ratio did not show an increased risk for the fellow eye while performing bilateral surgery, although not exempted from the risk of infection. It may be difficult to predict a complication in the fellow eye based on the results of the first operated eye.
authors.affiliation: The Michel Pop Clinics, Montreal, Quebec, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Pop
authors.forename: Y
authors.initials: Y
authors.lastname: Payette
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D019466:Glare; D006801:Humans; D054018:Lasers, Excimer; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D016017:Odds Ratio; D018903:Photorefractive Keratectomy; D011183:Postoperative Complications; D012029:Refraction, Ocular; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D014792:Visual Acuity