Effect of low-level light therapy in individuals with dry eye disease.

Introduction: Low-level light therapy (LLLT) or photobiomodulation, the application of red light to the eye, is used for the treatment of dry eye. Limited studies have investigated the efficacy of LLLT as a stand-alone treatment. The investigation aimed to evaluate the effect of LLLT on signs and symptoms of dry eye.

Methods: Participants with mild to moderate dry eye were recruited for this three-visit study. Visits were 7 (±3) days apart and all participants received 633 nm LLLT (eye-light®) for 15 min at each visit. Clinical measures including first and average non-invasive keratograph tear break-up time (NIKBUT), tear meniscus height (TMH), meibomian gland (MG) loss for upper and lower eyelids, ocular surface disease index (OSDI) score, tear film lipid layer thickness, meibum quality score, Schirmer's test, corneal fluorescein staining and eyelid temperature for external upper (EUL) and external lower (ELL) eyelids were measured from the right eye of participants before and after treatment.

Results: Thirty participants (mean [SD] age: 31.1 [9.5] years) completed the study. Treatment with LLLT resulted in significant differences in first and average NIKBUT, TMH, tear film lipid layer thickness, OSDI score, Schirmer's test, meibum quality score and eyelid temperature over time (all p < 0.05). Compared to baseline, TMH, tear film lipid layer thickness and eyelid temperature significantly increased by 0.06 mm (95% CI: 0.01-0.11), 12.9 nm (95% CI: 1.18-24.55), and 7.0°C, respectively, for both EUL (95% CI: 6.17-7.84) and ELL (95% CI: 6.17-7.73). The respective decrease in the OSDI score and Schirmer's test was 10.2 (95% CI: -15.15 to -5.26) and 4.4 mm (95% CI: -7.31 to -1.42; all p < 0.05). There was no significant difference in corneal fluorescein staining and MG loss after LLLT.

Conclusion: Low-level light therapy treatment significantly improved signs and symptoms of dry eye in the early phases of treatment, suggesting its efficacy for dry eye management.