How Effective is Keratorefractive Lenticule Extraction Surgery (KLEx) in Reducing Dry Eye Outcomes Compared to LASIK?: A Systematic Review and Meta-analysis

Purpose To evaluate the effectiveness of keratorefractive lenticule extraction (KLEx) in providing superior ocular surface protection compared to femtosecond laser–assisted laser in situ keratomileusis (FS-LASIK), focusing on key dry eye parameters such as tear break-up time (TBUT), Ocular Surface Disease Index (OSDI), Schirmer test, and corneal sensitivity. Methods A systematic search was conducted in PubMed, Scopus, Web of Science, and Embase in December 2024, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Inclusion criteria required human studies comparing KLEx (small incision lenticule extraction [SMILE]) and FS-LASIK with outcomes related to TBUT, OSDI, Schirmer test, and corneal sensitivity. Statistical analysis was performed using RevMan 5.3, employing a random-effects model to account for clinical heterogeneity. Heterogeneity was evaluated using Higgins' I 2 statistic, and publication bias was assessed through funnel plots. Results This meta-analysis, including 18 studies, compared KLEx (SMILE) and FS-LASIK in terms of dry eye parameters. The findings indicate that KLEx provides superior tear film stability, with significantly longer TBUT at 3 months (MD = 3.267 sec, P < .0001) and 6 months (MD = 3.320 sec, P < .0001). OSDI scores were slightly lower for KLEx, but the difference was not statistically significant. Schirmer test results (MD = 0.820 mm, P = .0001) favored KLEx, suggesting better tear production. KLEx also demonstrated better corneal sensitivity preservation, with significant differences at 1 (MD = 18.48, P < .0001) and 6 (MD = 7.56, P = .02) months, indicating less nerve damage. Sensitivity analyses confirmed the reliability of these findings. These results suggest that KLEx may be the preferable option for patients at risk of postoperative dry eye disease, offering better ocular surface stability and faster recovery. Conclusions KLEx offers significant advantages over FS-LASIK in TBUT and corneal sensitivity, indicating better tear film stability and nerve preservation. Both procedures yielded similar results for OSDI and Schirmer test outcomes. These findings suggest that KLEx may be a preferable option for patients at higher risk of postoperative dry eye disease. Future research should focus on standardized protocols and long-term follow-up to strengthen these conclusions.