Effect of tear film stability on fluctuation of vision after photorefractive keratectomy

PURPOSE: To evaluate the difference in tear film break-up between normal ey es and eyes after photorefractive keratectomy (PRK) and its impact on quali ty of vision in PRK eyes. METHODS: Seventy-seven normal eyes and 76 eyes with no ocular pathology exc ept refractive error that had PRK were enrolled. Tear film breakup time was determined under slit-lamp microscopy with fluorescent staining, Two video keratographs (TMS-1) were taken before and immediately after tear film brea k-up. Surface asymmetry index, surface regularity index, and subtractive ma ps were analyzed to evaluate corneal topographic changes before and after t ear film break-up. RESULTS: The distribution of tear film break-up in the central cornea was d ifferent 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 tempora l regions than in normal eyes; incidence of tear film break-up in the centr al cornea was decreased. There were no significant differences in tear film break-up between normal eyes and eyes after PRK (P = .69), Twelve PRK pati ents (24 eyes, 32%) experienced fluctuation of vision and fatigue during no rmal activities after PRK. We divided eyes after PRK into two groups (with and without fluctuation of vision) and found a statistically significant di fference in surface asymmetry index before tear film break-up between the t wo groups (P = .0092). CONCLUSION: The distribution of Lear film breakup is changed after PRK. Eye s after PRK experienced more fluctuation of vision than normal eyes.