Perioperative low-level light therapy for ocular surface protection in patients undergoing Femto-LASIK: a prospective double-masked, randomized controlled study

Background: Dry eye disease (DED) is among the most common complications experienced after femtosecond laser-assisted in situ keratomileusis (Femto-LASIK), often affecting visual recovery, as well as patient satisfaction. Low-level light therapy (LLLT) has shown benefits in various ocular surface diseases, but its role in refractive surgery remains underexplored. This study aimed at evaluating the efficacy of perioperative LLLT in preserving tear film parameters and reducing ocular discomfort symptoms after Femto-LASIK. Methods: In this prospective multicentric, randomized, double-masked, sham-controlled clinical study, adult patients undergoing Femto-LASIK were randomized (1:1) to receive periocular LLLT (633 ± 10 nm, 15 min/session) or sham treatment 7 ± 2 days before and after surgery. Ocular surface evaluation was performed at baseline (T0), and 1 week (T1), 1 month (T2), and 3 months (T3) postoperatively. Outcomes were tear meniscus height (TMH), Schirmer test values, and Dry Eye Questionnaire-5 (DEQ-5) scores, noninvasive tear break-up time (NIBUT), and interferometry. Results: Forty eyes of 40 patients (mean age: 34.58 ± 5.67 years) were analyzed. In the LLLT group, tear film parameters and subjective symptoms remained stable throughout follow-up, with no statistically significant changes over time. Conversely, the control group showed a significant decline in TMH (0.27 ± 0.05 mm to 0.20 ± 0.05 mm; p < 0.001), Schirmer test (20.39 ± 10.84 mm/5’ to 15.65 ± 9.02 mm/5’; p = 0.022), and a significant worsening in DEQ-5 scores (3.53 ± 4.10 to 5.94 ± 2.79; p = 0.005). Between-group comparisons demonstrated in the LLLT group significantly higher TMH at T2 ( p = 0.034) and T3 ( p = 0.016), higher Schirmer values at T2 ( p = 0.048) and T3 ( p = 0.018), and lower DEQ-5 scores at T1 ( p = 0.041), T2 ( p = 0.029), and T3 ( p = 0.018). NIBUT and interferometry showed no significant between-group differences at any time point. No treatment-related adverse events were observed. Conclusion: Perioperative LLLT appears to be a safe and well-tolerated adjunctive treatment that may help preserve tear volume and support postoperative comfort after Femto-LASIK. These findings suggest a potential role for LLLT in perioperative refractive surgery care, although further studies are warranted to confirm its clinical benefit.