To determine possible differences in dry eye syndrome in relation to surgery methods, especially between small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), in Korean patients.

This study involved 20 patients (20 eyes) who were treated with SMILE surgery and 23 patients (23 eyes) who were treated with FS-LASIK. The Schirmer test, tear film breakup time (TBUT), corneal staining score (CSS), and measurement of changes in the lipid layer thicknesses at one week, and 1 and 3 months after surgery were performed. Possible correlations between indicators of dry eye syndrome were then analyzed.

There was a significant time difference in some indices. The TBUT was 5.52 ± 1.50 s after one week for SMILE patients and 4.59 ± 2.50 s for FS-LASIK patients ( p = 0.02). The CSS was 0.50 ± 0.51 after 1 week for SMILE patients and 1.14 ± 0.99 after 1 week for FS-LASIK patients ( p = 0.04). The CSS was 0.50 ± 0.51 after 1 month for SMILE patients and 1.10 ± 0.93 after 1 month for FS-LASIK patients ( p = 0.03). Three months later, the CSS was 0.39 ± 0.50 for SMILE patients and 0.94 ± 0.85 for FS-LASIK patients ( p = 0.03). However, the Schirmer test did not show a significant difference postoperatively for SMILE and FS-LASIK patients at 1 week ( p = 0.44), 1 month ( p = 0.68), and 3 months ( p = 0.23). Additionally, the thickness of the tear film lipid layer did not show a significant difference during the same periods ( p = 0.36, p = 0.43, and p = 0.72, respectively).

When compared with FS-LASIK surgery, SMILE surgery resulted in significantly improved test results in the TBUT and CSS for dry eye syndrome.