Comparison of tear secretion and tear film instability after photorefractive keratectomy and laser in situ keratomileusis

Purpose: To evaluate and compare tear secretion and lear film instability f ollowing photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Setting: Department of Ophthalmology, Yonsei University School of Medicine, Seoul, Korea. Methods: In a prospective study, 36 eyes (21 patients) had PRK and 39 eyes (25 patients) had LASIK to correct myopia. Tear secretion and lear film ins tability were tested preoperatively and 3 and 6 months postoperatively usin g Schirmer test values, tear breakup time (BUT) scores, and tear osmolarity . Results: Six months after surgery. the change in Schirmer test values from preoperative levels was -14.57% +/- 6.39% (SD) in the PRK eyes and -23.40% +/- 5.94% in the LASIK eyes and the change in BUT scores, -12.54 +/- 8.28% and -18.79% +/- 13.01%, respectively. The change in tear osmolarity was 14. 95% +/- 6.46% and 35.63% +/- 8.51%, respectively. Conclusions: The decrease in tear secretion was greater after LASIK than af ter PRK at 6 months. Proper treatment of dry eye is required after LASIK an d PRK, particularly in the LASIK postoperative period. (C) 2000 ASCRS and E SCRS.