Low-level light therapy alters tear film measures and MMP-9 levels in dry eye pilot study

Low-level light therapy (LLLT) alone is associated with measurable improvements in tear film clinical measures and a significant reduction in tear MMP-9 levels in patients with mild to moderate dry eye disease (DED), according to a study.

The study included 30 participants with mild to moderate DED who received a 15-minute LLLT session once weekly for 3 weeks using the Eye-light EPI-C Plus device. Tear samples were collected at baseline and after the final treatment, and 10 inflammatory proteins were quantified using a multiplex bead-based assay. Clinical measures included first and average non-invasive keratograph tear break-up time (NIKBUT), tear meniscus height (TMH), tear film lipid layer thickness (TFLLT), and Schirmer’s test.

After the final LLLT session, all clinical measures showed statistically significant changes from baseline, including first and average NIKBUT (mean fold change [SD]: 1.6 [0.9] and 1.4 [0.7]), TMH (1.2 [0.3]), TFLLT (1.3 [0.4]), and Schirmer’s test (0.9 [0.5]) (all P < 0.05).

Among the inflammatory markers analyzed, only MMP-9 showed a significant change, with a reduction after treatment (mean log2 fold change [SD]: −0.7 [1.5]; P = 0.005).

No significant differences were detected in the other analytes. In addition, no correlations were found between changes in MMP-9 levels and changes in clinical measures (all P > 0.05).

Reference
Antwi A, Redfern R, Ritchey ER. Analysis of tear inflammatory proteins following Low-Level light therapy in dry eye disease patients. Cont Lens Anterior Eye. 2026;102629. doi: 10.1016/j.clae.2026.102629. Epub ahead of print. PMID: 41667355.