title: The safety and efficacy of photorefractive keratectomy after laser in situ keratomileusis.
abstract: OBJECTIVE
  To determine the safety and efficacy of performing photorefractive keratectomy (PRK) in corneas previously treated with laser in situ keratomileusis (LASIK) surgery.
  
  
  METHODS
  Fifteen eyes of 14 patients who had initially received LASIK for the treatment of myopia and compound myopic astigmatism were evaluated. Variables included existence of and/or type of flap complication associated with the original LASIK procedure, refractions before and after (3 and 6 months) PRK, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and the development of complications after PRK such as haze, scarring, double vision, or ghosting.
  
  
  RESULTS
  All 15 eyes were available for analysis at 6 months. Eleven eyes had experienced flap complications during the initial LASIK procedure and 4 eyes had experienced complications in the LASIK postoperative period. Characteristics prior to performing PRK included 11 myopic and 4 hyperopic eyes. By 6 months after PRK treatment, 87% of eyes had UCVA > or = 20/40, 53% had > or = 20/25, and 40% had > or = 20/20. All eyes had BSCVA of > or = 20/30, with 73% being > or = 20/20. No eye had lost 2 lines of BSCVA and only 1 eye lost 1 line of BSCVA. Sixty percent of eyes were within 1.0 diopters (D) of emmetropia, and 40% were within 0.5 D of emmetropia. A trend towards undercorrection and surgical induction of astigmatism as confirmed by vector analysis was noted. No eye developed significant haze or scarring.
  
  
  CONCLUSIONS
  Photorefractive keratectomy may be a safe procedure to perform in corneas previously treated with LASIK surgery. Results show good reduction of refractive error and improvement of UCVA and BSCVA. A significant undercorrection of astigmatism was attributed to surgically induced astigmatism. Further studies are necessary to determine the long-term safety and stability of outcomes.
authors.affiliation: Department of Ophthalmology, Henry Ford Health Systems, Detroit, MI 48083, USA.
authors.forename: Naazli M
authors.initials: NM
authors.lastname: Shaikh
authors.forename: Curt E
authors.initials: CE
authors.lastname: Wee
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Kaufman
mesh_terms: D001251:Astigmatism / Q000150:complications / Q000601:surgery*; D003315:Cornea / Q000601:surgery*; D006801:Humans; D007431:Intraoperative Complications; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D054018:Lasers, Excimer; D018903:Photorefractive Keratectomy / Q000379:methods*; D011183:Postoperative Complications; D012030:Refractive Errors / Q000150:complications; D054140:Refractive Surgical Procedures; D012086:Reoperation; D012449:Safety; D016896:Treatment Outcome; D014792:Visual Acuity