Effect of Low-Level Light Therapy on Ocular Surface Parameters in Patients Undergoing Femto-Lasik Surgery

Overview

This study evaluates the role of perioperative low-level light therapy (LLLT) in reducing dry eye disease (DED) symptoms after femtosecond laser-assisted in situ keratomileusis (Femto-LASIK). DED is one of the most frequent complications following Femto-LASIK, potentially affecting both visual recovery and patient satisfaction. In this prospective, multicenter, randomized, double-masked, sham-controlled trial, adult patients undergoing Femto-LASIK were assigned to receive either periocular LLLT (Eye-light® )or sham treatment before and after surgery. Tear film parameters and ocular surface symptoms were assessed at baseline, 1 week, 1 month, and 3 months postoperatively. Results showed that patients treated with LLLT maintained stable tear volume and reported fewer ocular discomfort symptoms compared with controls, who experienced significant declines. No adverse events related to LLLT were observed. These findings suggest that perioperative LLLT is a safe and well-tolerated approach that may help preserve tear film stability and improve postoperative comfort in Femto-LASIK patients.

This multicenter, randomized, double-masked, sham-controlled clinical trial was conducted to evaluate the efficacy and safety of perioperative low-level light therapy (LLLT) in preventing dry eye disease (DED) symptoms in patients undergoing femtosecond laser-assisted in situ keratomileusis (Femto-LASIK). The study was performed between August 2024 and June 2025 at the Centro Vista Eye Clinic and the Cai Ferate Clinical Hospital (Iași, Romania) in accordance with the Declaration of Helsinki and institutional ethics approval. Dry eye disease is a multifactorial condition characterized by tear film instability, ocular surface inflammation, and neurosensory abnormalities. It is among the most common complications after corneal refractive surgery, largely due to the transection of corneal nerves during flap creation and excimer laser ablation, which disrupts the lacrimal functional unit and reduces tear production. This can impair visual recovery and reduce patient satisfaction. LLLT is a non-invasive photobiomodulation technique that delivers low-intensity, monochromatic red light (633 ± 10 nm) to periocular tissues. It has been shown to improve mitochondrial function, modulate inflammatory pathways, and enhance meibomian gland activity, with potential benefits in ocular surface disease. Its role in the perioperative management of DED after LASIK, however, has not been fully explored. Eligible participants were consecutive adults (≥18 years) scheduled for Femto-LASIK. Exclusion criteria included pre-existing ocular surface disease or DED, prior ocular surgery, autoimmune disease, use of systemic medications associated with DED, and any intraoperative or postoperative complications that could interfere with evaluation. Both eyes of each patient were included in the analysis. Participants were randomized (1:1) to receive either LLLT or sham treatment. LLLT was administered with the Eye-light® device (Espansione Marketing S.p.A., Italy) for 15 minutes one week before and one week after surgery. Sham-treated patients underwent the same procedure with less than 30% of the treatment power, ensuring masking. All surgeries were performed by experienced surgeons using standardized LASIK techniques under topical anesthesia, followed by a uniform postoperative regimen including topical antibiotics, corticosteroids, and preservative-free artificial tears. Clinical assessments were performed at baseline (T0), 1 week postoperatively (T1), 1 month (T2), and 3 months (T3). Parameters included: Non-invasive tear break-up time (NIBUT) Tear meniscus height (TMH) Lipid layer interferometry Schirmer I test Dry Eye Questionnaire-5 (DEQ-5) The primary outcome was the preservation of tear volume and ocular surface parameters at 3 months postoperatively. Secondary outcomes included changes in patient-reported symptoms and tear film stability. Safety was evaluated by monitoring treatment-related adverse events and tolerability. Statistical analysis was conducted using SPSS (version 30.0). Non-parametric and parametric tests were applied as appropriate, with p \< 0.05 considered statistically significant. Sample size calculation ensured adequate power (\>0.99) to detect clinically meaningful effects. A total of 61 patients were randomized, of whom 40 (80 eyes) completed the study (23 in the LLLT group, 17 in the sham group). Patients receiving LLLT showed preserved tear meniscus height, stable Schirmer test values, and unchanged DEQ-5 scores over 3 months, whereas the sham group demonstrated significant deterioration in these parameters. No significant effects were found for NIBUT or interferometry. No treatment-related adverse events were reported, and LLLT was well tolerated. This is the first prospective randomized trial to evaluate perioperative LLLT in Femto-LASIK patients. The results suggest that LLLT may protect ocular surface health, preserve tear volume, and improve patient comfort after refractive surgery. These findings support further research to optimize treatment protocols and confirm long-term benefits