Effect of Tear Film Stability on Fluctuation of Vision after Photorefractive Keratectomy

PURPOSE: 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 breakup 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).CONCLUSION: The distribution of Lear film breakup is changed after PRK. Eyes after PRK experienced more fluctuation of vision than normal eyes