Histological changes and unscheduled DNA synthesis in the rabbit cornea following 213-nm, 193-nm, and 266-nm irradiation.

PURPOSE: To examine the acute outcome of corneal irradiation in adult rabbits for 193-, 213-, and 266-nm laser wavelengths.
METHODS: Animals were randomly allocated to one of three groups and were treated with 213-nm quintupled Nd:YAG laser, a 193-nm excimer laser, or a 266-nm quadrupled Nd:YAG laser (n = 6 per group, two exposure durations). Thermal damage was assessed histologically and the extent of DNA damage estimated by measuring unscheduled DNA synthesis in corneal epithelial and stromal cells using 3H thymidine autoradiography.
RESULTS: For the 193- and 213-nm groups, irradiation did not induce thermal damage. Moreover, cells displaying unscheduled DNA synthesis represented < 4% of the total cell numbers with no difference between groups (P > .05). By contrast, the 266-nm laser led to stromal melting and vacuolation; unscheduled DNA synthesis levels were elevated over the other groups (P < .05).
CONCLUSIONS: Corneal laser ablation with the 213-nm Nd:YAG laser resulted in similarly low levels of thermal and DNA damage to those produced using the clinically accepted 193-nm excimer laser.