Incidence of femtosecond laser-assisted LASIK flap complications: A Systematic Review

This review evaluated the incidence and visual significance of flap-related complications in femtosecond LASIK.

Femtosecond laser-assisted LASIK has largely replaced mechanical microkeratomes for flap creation due to improved precision and safety. Understanding the incidence and clinical consequences of flap-related complications is essential for patient counseling and surgical planning.

A systematic search of Ovid MEDLINE, Embase, and CINAHL was conducted from database inception to October 10, 2024 including English-language clinical reports of patients undergoing femtosecond LASIK that reported flap-related complications. Small case series (<5 patients), secondary articles, conference abstracts, and cost-analysis studies were excluded. Study screening and data extraction were performed independently by two reviewers. The primary outcome was the incidence of LASIK flap complications stratified by femtosecond laser platform; secondary outcomes included postoperative visual acuity. Risk of bias was assessed at the outcome level using RoB 2 for randomized clinical trials and ROBINS-I for observational studies. Findings were synthesized narratively with descriptive summary of incidence proportions; no meta-analysis was performed due to heterogeneity in study designs and laser platforms. The review was registered in PROSPERO (CRD42024608238) with no post-submission amendments.

Twenty-seven studies published between 1997 and 2024 were included, comprising 28,531 eyes across multiple countries. The most frequently reported intraoperative event was opaque bubble layer, occurring in 19.7% of eyes (range 2.0-56.4%). Diffuse lamellar keratitis was reported in 6.3% of eyes and typically resolved without long-term visual impact. Epithelial ingrowth (2.1%), microstriae (1.6%), and incomplete flaps (0.17%) were uncommon. Other flap-related events, including buttonholes, free caps, epithelial defects, and traumatic flap injuries, were rare (<1%).

Femtosecond LASIK is associated with low rates of clinically significant flap-related complications, with excellent visual outcomes in most cases. Standardized reporting and longer-term prospective studies are needed to further refine complication benchmarks across femtosecond platforms.