Cooling effect on excimer laser photorefractive keratectomy

Purpose: To evaluate the effect of cooling on pain, corneal haze, and refractive outcome after excimer laser photorefractive keratectomy (PRK). Setting: Tokyo Medical and Dental University Hospital, Tokyo, Japan. Methods: The corneal surface was cooled before, during, and after laser ablation using a method called cooling PRK. Thirty-eight highly myopic eyes of 38 patients whose spherical errors ranged from -8.00 to -18.75 diopters (D) were randomized into 2 groups: 16 eyes with conventional PRK and 22 eyes with cooling PRK, Postoperative pain was measured using the Visual Analogue Scale (VAS). Refraction, visual acuity, and complications were followed for up to 2 years, Aii data were analyzed and compared between groups to evaluate the cooling effect on PRK. Results: One day postoperatively, patients in the cooling PRK group had significantly less pain (P < .01). At 3 months, the haze score in the cooling PRK group was significantly less than in the conventional PRK group (P < .01), The residual refractive error was not significantly different between the 2 groups until 2 years, when it was greater in the conventional PRK (mean -5.09 D +/- 2.11 [SD]) than the cooling PRK group (-4.64 +/- 2.27 D). Ten eyes (62.5%) in the conventional PRK group and 15 eyes (68.2%) in the cooling PRK group were within +/- 1.00 D of the intended refraction, There were no serious complications in the cooling PRK group. Two eyes in the conventional PRK group had severe corneal haze and lost 2 Snellen lines of best corrected visual acuity. Conclusion: Corneal cooling on PRK effectively reduced postoperative pain, corneal haze, and myopic regression. (C) 1999 ASCRS and ESCRS.