title: Effect of tear film stability on fluctuation of vision after photorefractive keratectomy.
abstract: OBJECTIVE
  To evaluate the difference in tear film break-up between normal eyes and eyes after photorefractive keratectomy (PRK) and its impact on quality of vision in PRK eyes.
  
  
  METHODS
  Seventy-seven normal eyes and 76 eyes with no ocular pathology except refractive error that had PRK were enrolled. Tear film break-up time was determined under slit-lamp microscopy with fluorescent staining. Two videokeratographs (TMS-1) were taken before and immediately after tear film break-up. Surface asymmetry index, surface regularity index, and subtractive maps were analyzed to evaluate corneal topographic changes before and after tear film break-up.
  
  
  RESULTS
  The distribution of tear film break-up in the central cornea was different in PRK eyes than in normal eyes (P < .0001). Distributions of tear film break-up after PRK were localized more in the upper and lower temporal regions than in normal eyes; incidence of tear film break-up in the central cornea was decreased. There were no significant differences in tear film break-up between normal eyes and eyes after PRK (P = .69). Twelve PRK patients (24 eyes, 32%) experienced fluctuation of vision and fatigue during normal activities after PRK. We divided eyes after PRK into two groups (with and without fluctuation of vision) and found a statistically significant difference in surface asymmetry index before tear film break-up between the two groups (P = .0092).
  
  
  CONCLUSIONS
  The distribution of tear film break-up is changed after PRK. Eyes after PRK experienced more fluctuation of vision than normal eyes.
authors.affiliation: Department of Ophthalmology, Provincial Hsin-Chu Hospital, Taiwan.
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: I J
authors.initials: IJ
authors.lastname: Wang
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D019781:Corneal Topography; D006801:Humans; D054018:Lasers, Excimer; D009216:Myopia / Q000503:physiopathology*; D018903:Photorefractive Keratectomy / Q000009:adverse effects*; D013666:Tears / Q000378:metabolism / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology*; D014792:Visual Acuity