title: Comparison of laser in situ ketatomileusis and photorefractive keratectomy for myopia using a mixed-effects model.
abstract: OBJECTIVE
  To compare the results of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for myopia using a mixed-effects model.
  
  
  METHODS
  This comparative retrospective study was conducted in 1,127 eyes of 579 patients after LASIK and 270 eyes of 144 patients after PRK who had two or more postoperative follow-ups after 3 months. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refractive spherical equivalent (MRSE), percentage of eyes within ± 0.5 diopters (D) and ± 1.0 D of targeted refraction, and central corneal thickness were compared between PRK and LASIK groups using a mixed-effects model.
  
  
  RESULTS
  Compared with the LASIK group, UCVA in the PRK group was significantly worse in the initial year but was significantly better after 4 years. The average BSCVA was not significantly different between the LASIK and PRK groups after 4 years. The average gain of BSCVA in the PRK group was significantly larger than that of the LASIK group after 2 years. MRSE in the LASIK and PRK groups showed a gradual myopic shift until 6 years after surgery. After 6 years, MRSE in the PRK group remained stable whereas MRSE in the LASIK group continued a myopic shift. The percentages of eyes within ± 0.5 D or ± 1.0 D in the LASIK group were significantly higher than those in the PRK group at 3 months but were significantly lower than those in the PRK group at 10 years.
  
  
  CONCLUSIONS
  PRK for myopia shows better efficacy than LASIK for myopia after 4 years.
authors.affiliation: Miyata Eye Hospital, Miyakonojo, Japan.
authors.forename: Yosai
authors.initials: Y
authors.lastname: Mori
authors.affiliation: Miyata Eye Hospital, Miyakonojo, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Miyata
authors.affiliation: Miyata Eye Hospital, Miyakonojo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ono
authors.affiliation: Miyata Eye Hospital, Miyakonojo, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yagi
authors.affiliation: Department of Ophthalmology, University of Kitasato School of Medicine, Kanagawa, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Kamiya
authors.affiliation: Inouye Eye Hospital, Tokyo, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Amano
mesh_terms: D000328:Adult; D016001:Confidence Intervals; D003315:Cornea / Q000601:surgery; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008297:Male; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000379:methods*; D011184:Postoperative Period; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult