Correlation between ultraviolet radiation level and the incidence of late-onset corneal haze after photorefractive keratectomy

Purpose: To investigate the correlation between environmental changes in ul traviolet (UV) radiation levels and the incidence of late-onset cornea haze (LOCH) after photorefractive keratectomy (PRK). Setting: SynsLaser Clinic, Tromso, Norway. Methods: The study comprised 404 eyes that had myopic PRK and photoastigmat ic refractive keratectomy from February 1996 through July 1998. The high la titude (70 degrees N) of the observation site provided "natural laboratory" conditions to look at the occurrence of LOCH with high and low W-radiation levels, which occurred during summers and winters, respectively. The diagn ostic criterion for LOCH was acute haze of grade greater than or equal to2 occurring between 4 and 12 months postoperatively. Results: The follow-up ranged from 12 to 41 months. Of the 314 eyes that me t the inclusion criteria, 11 developed LOCH when the environmental UV-radia tion level was high. No eye developed LOCH when the level was low. The corr elation between a high level of environmental UV radiation and the occurren ce of LOCH was statistically significant (P = .001). Conclusion: Environments with high UV-radiation levels may increase the ris k of LOCH after PRK in eyes with moderate to high myopia. Use of UV-protect ive eyewear should be encouraged during the first year after PRK. (C) 2001 ASCRS and ESCRS.