Regression-related factors before and after laser in situ keratomileusis.

The aim of this study was to evaluate the refractive regression-related factors before and after laser in situ keratomileusis (LASIK) for myopia and give a reasonable way to prevent it. The consecutive patients who underwent LASIK from January to June 2004 were reviewed retrospectively. Thirteen eyes from 8 patients with myopic regression and 60 eyes from 42 patients with no myopic regression within 12 months of follow-up were enrolled. We compared the pre- and postoperative data which were associated with regression in the two groups. The mean preoperative intraocular pressure (IOP) was significantly higher in the regression group than in the non-regression group (p = 0.03). During the period of 12 months, the two groups differed in corneal bowing. In the regression group, both posterior and anterior corneal surfaces were significantly bowing (all p < 0.05). In contrast, in the non-regression group, both posterior and anterior surfaces were relatively stable (all p > 0.05). The higher preoperative IOP and the progressive postoperative biomechanical bowing in the posterior and anterior surfaces of the cornea are two factors related to myopic regression in this study. Lowering the IOP preoperatively and postoperatively may be an effective way to prevent the myopic regression after LASIK.