Regional changes in corneal shape over a 6-month follow-up after femtosecond-assisted LASIK

Abstract

To assess the regional changes in corneal shape after femtosecond laser-assisted laser insitu keratomileusis (FS-LASIK) in patients with different myopia extents. Eye Hospital, Wenzhou Medical University, Wenzhou, China. Retrospective case series. A retrospective study of myopic eyes treated with FS-LASIK was conducted to assess the shape changes within different corneal regions after surgery. Corneal curvature was measured in the central region (0mm to 3.0mm diameter), pericentral region (3.0mm to 6.0mm diameter) and peripheral region (6.0mm to 9.0mm diameter) preoperatively and from 1week to 6months postoperatively. The study comprised 608 myopic eyes. During the 6-month follow-up, the anterior cornea became steeper in the central and pericentral regions, but flatter in the peripheral region (P<.01), representing a partial, gradual, yet significant reversal of the immediate change in corneal shape after laser ablation. In contrast, the posterior surface experienced significantly less change than the anterior surface, with the cornea becoming slightly flatter (P<.01) in the central region at 1week postoperatively, and steeper elsewhere (P<.05), and then remaining stable during the rest of the follow-up. On the other hand, the anterior astigmatism had significant decreases in the central region (P<.01) and slight increases in the peripheral region (P<.01) 1week postoperatively, and that remained stable over the follow-up period. In contrast, there were little or non-significant changes in the posterior astigmatism throughout the follow-up (P>.05). Postoperative corneal shape changes were different in different regions. There were shape changes in individual corneal regions during the 6-month follow-up period that represented reverse trends; however, the changes were much smaller than the short-term changes observed 1week after surgery.