Effect of Low-Level Light Therapy on Ocular Surface Parameters in Patients Undergoing Cataract Surgery: A Prospective Double-Masked Randomized Controlled Clinical Trial

Introduction: Postoperative dry eye disease (DED) remains a frequent complication that can reduce patient satisfaction and surgical outcomes. Low-level light therapy (LLLT) is a non-invasive technology that has shown positive outcomes in managing DED. This study aimed to assess the prophylactic application of perioperative LLLT for improving ocular surface parameters and symptoms in consecutive patients undergoing cataract surgery. Methods: In this prospective, double-masked, randomized sham-controlled study, patients scheduled for cataract surgery were randomized to receive either periocular LLLT or sham treatment 1 week before and 1 week after surgery. Ocular surface assessments, including Ocular Surface Disease Index (OSDI) questionnaire, tear film break-up time (BUT), Schirmer test type I, tear osmolarity, and corneal fluorescein staining (Oxford score), were performed preoperatively before the first treatment/sham session (T0), and postoperatively 1 week (T1) and 1 month postoperatively (T2). All patients received the same postoperative therapy. Results: Out of 98 patients randomized to LLLT (50 patients) or sham treatment (48 patients), 89 patients (45 males, 44 females; mean age of 73.75 ± 7.95 years) completed the study. Unlike controls, the LLLT group showed significant improvements from T0 to T1 and T2 for OSDI scores (respectively, from 26.62 ± 15.42 to 15.53 ± 12.04 and 13.36 ± 11.69; p < 0.001) and BUT values (respectively, from 5.76 ± 3.99 to 6.69 ± 4.48 and 8.38 ± 4.53; p = 0.002), and from T0 to T2 for tear osmolarity (respectively, from 300.69 ± 14.19 mOsm/l to 296.11 ± 12.30 mOsm/l; p = 0.048). No significant differences were found in Schirmer test values within or between the two groups. No adverse effects were reported. Conclusions: Perioperative LLLT is a safe, well-tolerated, and effective treatment for preventing iatrogenic DED in cataract surgery. Integrating LLLT into the routine perioperative care may enhance patient satisfaction and overall outcomes in the setting of cataract surgery. Clinical Trial Registration Number: NCT07067294, retrospectively registered on 05.07.2025.