LASIK, SMILE induce epithelial thickening in patients with myopia

This prospective randomized study compared the 3-dimensional epithelial remodeling in patients undergoing LASIK versus small incision lenticule extraction (SMILE).

Study design

The study included 21 patients (42 eyes) with myopia; one eye received LASIK while the fellow eye received SMILE. Inclusion criteria were spherical error between −3 and −10 D), and astigmatism between 0 to −6 D. Researchers performed corneal epithelial mapping with anterior segment OCT over a period of 2 years. LASIK was performed with a topography-guided system using a femtosecond laser for flap creation.

Outcomes

Central epithelial thickness increased from 52.38 μm at baseline to 57.00 μm at 2 years in the LASIK group and from 52.52 μm to 57.15 μm in the SMILE group. This thickness remained stable from 3 to 24 months postoperatively in both groups. Both procedures created a similar level and pattern of epithelial thickening, including a significant increase in mid-peripheral epithelial thickness.

Although the differences between pre- and postoperative changes were significant, there were no differences between the 2 techniques at any time. The zonal area 2 to 5 mm from the center was more affected in LASIK eyes, whereas the zonal area from 5 to 6 mm was more affected in SMILE eyes.

Limitations

This study provides helpful data that corroborate findings from other similar studies, however the study size was small. A true control group—a group that underwent femtosecond treatment of the cornea but otherwise had a sham refractive treatment—was not present.

Clinical significance

Both LASIK and SMILE resulted in very similar epithelial thickening. These findings suggest that epithelial remodeling may correlate with corneal curvature changes associated with these procedures rather than the difference in subepithelial corneal denervation between LASIK and SMILE.