Changes in intraocular pressure and anterior chamber dimensions after 5-years of corneal refractive surgery.

This study aims to evaluate intraocular pressure (IOP) and anterior chamber dimensions (ACD) changes occurred after a 5-year period post femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE). Totally, 713 eyes of 361 myopic patients and 424 eyes of 212 control arms were retrospectively enrolled and classified into different groups according to the surgery methods and degrees of myopia. Of which, 549 underwent SMILE and 164 underwent FS-LASIK. IOP and AC indicators were tested. Depth (ACD), AC angle (ACA), AC volume (ACV) and central corneal thickness were evaluated before and 5-years post operation. The magnitudes of IOP, ACD, ACA, ACV and central corneal thickness decreased significantly postoperatively (all P < .05). In both of SMILE and FS-LASIK groups, postoperative ACDs were all significantly shallower (P < .001) and ACVs significantly decreased (P < .001), while ACA was merely significantly narrowed in SMILE group. Only in the high spherical equivalent (SE) group, could we found significant difference between SMILE and FS-LASIK group in terms of △ACV (P < .01) and △ACD (P < .001), respectively. Compared with moderate SE and high SE groups, low SE group showed a relatively significant difference between preoperative and postoperative ACA. After adjusted for many parameters preoperatively, △IOP was positively correlated with preoperative SE and all of the 4 mentioned variables (△IOP,△ACD,△ACA and△ACV) were negatively correlated with their corresponding preoperative indicators. IOP and AC parameters decreased significantly after refractive surgery. Corneal deformation and AC remodeling may account for these changes. FS-LASIK resulted in a smaller decrease in AC parameters than SMILE in high myopia patients, suggesting less anterior segment remodeling.