Corneal Endothelial Morphometric Changes after Laser in Situ Keratomileusis with Residual Thickness less than 250 micro meter

ABSTRACT

PURPOSE: To evaluate endothelial cell changes following LASIK with residual corneal thickness of less than 250 micro meter. METHOD: We performed noncontact specular microscopy preoperatively, and 1 week, 1, 3, 6, 9 months after surgery to examine 82 eyes which had undergone LASIK. Corneal endothelial density (CD), coefficient of variation of the cell area (CV), and the percentage of hexagonal cells(hexagonality, 6A) were obtained according to the corneal endothelial cell analysis program. Analysis was done according to the parameters such as residual stromal bed thickness, number of laser pulse and percentage of ablated stromal thickness and preoperative spherical equivalent. RESULTS: Changes in CD and CV showed no significant difference throughout the follow-up period after surgery. Hexagonality, however, decreased after surgery. In particular, corneas with residual thickness of less than 235 micro meter or the number of laser pulse over than 400, or ablation more than 30% of stromal thickness showed significant decrease in hexagonality. CONCLUSIONS: This results suggest that LASIK with deep ablation might cause corneal endothelial damages, and at least 235 micro meter or more of residual thickness should be preserved to avoid endothelial damages.