title: Stereoacuity after photorefractive keratectomy in myopia.
abstract: OBJECTIVE
  Stereopsis, as a part of visual function, is the ability of differentiating between the two eyes' views (binocular disparity), due to the eyes' different positions. The aim of this study was to compare stereoscopic vision before and after photorefractive keratectomy (PRK) in myopia.
  
  
  METHODS
  In a prospective interventional case series study clinical trial, forty-eight myopic individuals (age range: 18-34 years) who had undergone PRK surgery by a Bausch & Lomb Technolas 217z excimer laser were included. In all patients, stereoscopic vision was assessed using TNO test charts at 40 cm distance preoperatively and at 3 and 6 months postoperatively.
  
  
  RESULTS
  A total of 48 cases (96 eyes, 69% female) with a mean age of 26.70 ± 4.89 years (range: 18-34 years) were treated. Uncorrected visual acuity (UCVA) was improved and refraction was corrected significantly after PRK surgery. The stereoscopic vision in patients was 246.56 ± 98.43 s of arc before PRK surgery. Postoperatively, the stereoacuities were recorded as 365.38 ± 112.65 s of arc and 343.51 ± 88.96 s of arc at 3 and 6 months, respectively. These differences were statistically significant (p < 0.001).
  
  
  CONCLUSIONS
  PRK was successful and safe in improving refractive error and UCVA, but it may deteriorate the stereoscopic vision. It may be due to an increase in higher order aberrations.
authors.affiliation: Cornea Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Siamak
authors.initials: S
authors.lastname: Zarei-Ghanavati
authors.affiliation: Cornea Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Gharaee
authors.affiliation: Cornea Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Eslampour
authors.affiliation: Refractive Error Research Center, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran; Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Asieh
authors.initials: A
authors.lastname: Ehsaei
authors.affiliation: Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Abrishami
keywords: Myopia; Photorefractive keratectomy; Stereoscopic vision