Combined flap undersurface and bed LASIK for high myopia

PURPOSE: To discuss the predictability, stability and safety of LASIK for high myopia using laser treatment on both the flap undersurface and bed (both-sided LASIK). METHODS: One hundred twenty-one eyes of 63 patients underwent flap undersurface and bed LASIK for high myopia. Postoperative uncorrected visual acuity (UCVA), refraction, and topography were evaluated up to 12 months. The safety and injury indices in both-sided LASIK were compared with that of conventional LASIK. RESULTS: In both-sided LASIK, the largest diopter correction on the undersurface of the corneal flap was -6.00 diopters (D), correlating to an ablation of 44.62 mu m. The mean thickness of residual corneal stroma bed was 283.87 +/- 19.83 mu m after the laser treatment. Postoperative UCVA was close to the preoperative best spectacle-corrected visual acuity (BSCVA). The mean BSCVA was significantly better (P < .05) than preoperatively at each time point (1 week, 1, 3, and 6 months, and 1 year) after surgery. Postoperative corneal topography was normal in all cases. The safety and injury indices for conventional LASIK in both-sided LASIK eyes were calculated by programming the excimer laser as though conventional treatments would be performed to calculate the theoretical bed ablation. The safety factor of both-sided LASIK was higher than that calculated for conventional LASIK (P < .05); the injury index was lower than that calculated for conventional LASIK (P < .05). CONCLUSIONS: Surgery on high myopia by both sided LASIK is safe and effective.