title: Correlation between practice location as a surrogate for UV exposure and practice patterns to prevent corneal haze after photorefractive keratectomy (PRK).
abstract: BACKGROUND
  PRK is a refractive surgery that reshapes the corneal surface by excimer laser photoablation to correct refractive errors. The effect of increased ultraviolet (UV) exposure on promoting post-PRK corneal haze has been reported in the literature; however, information is lacking regarding the effect of ambient UV exposure on physician practice patterns. The aim of this study was to evaluate the effect of ophthalmologists' practice location on their reported practice patterns to prevent post-PRK corneal haze.
  
  
  METHODS
  A cross-sectional observational study was conducted through an online survey sent to ophthalmologists performing PRK. The survey recorded the primary city of practice from which the two independent variables, latitude and average annual sunshine days, were determined. It also measured the frequency of use of postoperative preventive interventions (dependent variables) which are as follows: intraoperative Mitomycin-C, oral vitamin C, sunglasses, topical corticosteroids, topical cyclosporine, oral tetracyclines and amniotic membrane graft.
  
  
  RESULTS
  Fifty-one ophthalmologists completed the survey. Practice locations' mean latitude was 36.4 degrees north, and average sunshine days annually accounted for 60% of year days. There was no significant relation between latitude/average annual sunshine days and usual post-PRK prophylactic treatments (P> 0.05). The commonest protective maneuvers were sunglasses (78%), prolonged topical corticosteroids (57%), Mitomycin-C (39%) and oral vitamin C (37%).
  
  
  CONCLUSIONS
  We found no significant difference in ophthalmologists' practice patterns to prevent post-PRK corneal haze in relation to practice location latitude and average sunshine days. Moreover, the results demonstrated that the most widely used postoperative measures to prevent post-PRK haze are sunglasses, Mitomycin-C, topical corticosteroids, and oral Vitamin C.
authors.affiliation: King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia; King Saud University College of Medicine, Riyadh, Saudi Arabia.
authors.forename: Eman M
authors.initials: EM
authors.lastname: Al-Sharif
authors.affiliation: King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia; Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, United States.
authors.forename: Donald U
authors.initials: DU
authors.lastname: Stone
keywords: Corneal haze; IRB, Institutional Review Board; Mitomycin; PRK, photorefractive keratectomy; Photorefractive keratectomy; Refractive surgery; UV; UV, ultraviolet