LASEK leads to greater forward shift of posterior cornea than LASIK, study finds

LASEK resulted in a greater forward shift of the posterior corneal surface than LASIK, a study using corneal mapping found. The posterior surface gradually shifted back toward its original position over time but never returned to its preoperative position, the study authors said.

Hyojin Kim and colleagues at The Catholic University of Korea studied 22 eyes of 14 patients who underwent LASIK and 19 eyes of 10 patients who underwent LASEK to compare the degree of forward shift of the posterior corneal surface as a function of time after surgery. Uncorrected visual acuity, spherical equivalent and pachymetry were obtained before and 1 or 2 weeks and 2, 6, 12 and 24 months after surgery. Corneal elevation was assessed using the Bausch & Lomb Orbscan II.

At 1 or 2 weeks postop, the posterior corneal surface had shifted forward by 18 µm in eyes that underwent LASIK. At the same time point, the posterior corneal surface had shifted forward by 25.9 µm in eyes that underwent LASEK. The mean posterior corneal shift was reduced by 3.05 µm in the LASIK group and by 12.4 µm in the LASEK group at 2 years postop. In neither group did the forward shift return to the elevation observed before surgery.

The study is published in the January issue of Ophthalmologica.