title: Evaluation of photorefractive keratectomy retreatments after regressed myopic laser in situ keratomileusis.
abstract: OBJECTIVE
  To evaluate the results of photorefractive keratectomy (PRK) enhancements in eyes previously treated by myopic laser in situ keratomileusis (LASIK) showing an undercorrection due to either a refractive regression or a primary undercorrection, when an in-the-bed enhancement was not advisable because of residual stromal thickness limitations.
  
  
  METHODS
  Noncomparative, prospective, interventional case series.
  
  
  METHODS
  Seventeen eyes of 17 patients previously treated by LASIK for a spherical equivalent (SE) correction of -8.125 to -12.50 diopters (D; mean, -9.45 +/- 1.01 D), that after a follow-up of 6 to 14 months ended up with a refraction of -1.50 to -3.75 D (SE; mean, -2.48 +/- 0.74 D). Intended flap thickness was 160 microm for all eyes. In all cases, the residual stromal bed under the flap was considered too thin (255-305 microm) to allow an in-the-bed enhancement without exceeding an assumed safety thickness limit (250 microm).
  
  
  METHODS
  Eyes were treated by PRK at least 6 months after LASIK. The PRK ablation parameters (diameter, attempted correction) were selected to avoid theoretical flap perforation. The deepest ablation was 60 microm, for a -3.75-D correction. We used a Bausch & Lomb 217 C excimer laser (Bausch & Lomb, Rochester, New York).
  
  
  METHODS
  Refraction, uncorrected and best-corrected visual acuity (BCVA), slit-lamp evidence of corneal opacity or other visible complications, and corneal topography.
  
  
  RESULTS
  Although the initial postoperative period was characterized by very satisfactory refractive results (mean SE error at 1 month, -0.04 +/- 0.37 D; range, +0.75 to -0.625 D), during follow-up, a dense haze (grade 3 and 4) developed in 14 eyes (82.3%) that induced a further myopic regression (SE, -1.725 to -5.50 D; mean, -3.11 D) and BCVA loss (two to six lines). These 14 eyes underwent a further surgical treatment to remove the severe haze at 3 to 10 months after PRK.
  
  
  CONCLUSIONS
  Based on these results, we strongly advise against PRK as a possible option to correct eyes previously treated by myopic LASIK that resulted in an undercorrection.
authors.affiliation: The Carones Ophthalmology Center, Milan, Italy. fcarones@micronet.it
authors.forename: F
authors.initials: F
authors.lastname: Carones
authors.forename: L
authors.initials: L
authors.lastname: Vigo
authors.forename: A V
authors.initials: AV
authors.lastname: Carones
authors.forename: R
authors.initials: R
authors.lastname: Brancato
mesh_terms: D000328:Adult; D003315:Cornea / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000209:etiology / Q000601:surgery*; D018903:Photorefractive Keratectomy; D011183:Postoperative Complications; D011446:Prospective Studies; D012008:Recurrence; D012029:Refraction, Ocular; D012086:Reoperation; D016896:Treatment Outcome; D014792:Visual Acuity