CORNEAL ENDOTHELIAL CHANGES AFTER LASER IN-SITU KERATOMILEUSIS

Purpose: To ascertain whether 193 nm excimer laser in situ keratomileu sis (LASIK) to correct high myopia causes in vivo changes in the human corneal endothelium 3 and 6 months after surgery. Setting: Alicante I nstitute of Ophthalmology, University of Alicante, Spain. Methods: Pre operative and serial postoperative specular microscopy of the central corneal endothelium was done in 33 eyes of 19 patients (Group I)with a mean age of 34.3 years +/- 10.6 (SD) (range 20 to 60 years) who had L ASIK to correct myopia of between 8.25 and 18.50 diopters (D) (mean 11 .90 +/- 2.20 D). Twelve patients (20 eyes) were contact lens wearers ( Group 2), and 7 (13 eyes) had never worn contact lenses (Group 3). The central endothelium was analyzed for several parameters including cel l density, coefficient of variation in cell size, and hexagonality. Th e data obtained before surgery were compared with those obtained after surgery in all groups. Results: There was no significant difference i n age, sex, and preoperative myopia between Groups 2 and 3. In Group 1 , mean cell density was significantly higher (3.5%) 6 months after sur gery (P = .017) and the coefficient of variation decreased 3 and 6 mon ths after surgery (P < .001); no significant changes were noted in the percentage of hexagonal cells. In Group 2, there was a significant in crease in cell density (4.8%) 6 months after surgery (P = .010) and th e coefficient of variation decreased at 3 and 6 months after surgery ( P < .001); the hexagonality did not change postoperatively. In Group 3 , there were no significant differences between preoperative and posto perative mean cell density, coefficient of variation, or hexagonality. Conclusion: Laser in situ keratomileusis caused no damage to the cent ral corneal endothelium. Postoperative improvements in the endothelial cell density and the coefficient of variation in cell size values wer e related to the discontinuance of contact lens use after surgery.