Low-level light therapy for dry eye disease and meibomian gland dysfunction: A systematic review and meta-analysis.

A healthy tear film is vital for ocular surface integrity and relies on the coordinated function of the lacrimal glands, meibomian glands and conjunctival goblet cells. Dysfunction in any of these elements can lead to dry eye disease (DED). This systematic review and meta-analysis evaluated the efficacy of low-level light therapy (LLLT) as a standalone DED treatment. Although evidence for LLLT's therapeutic potential is growing, prior reviews have focused on short-term outcomes or combined LLLT with intense pulsed light. This meta-analysis consolidates current findings to clarify the clinical value of LLLT monotherapy in DED management. We systematically searched MEDLINE, Embase, Scopus and the Cochrane Central Register of Controlled Trials for studies evaluating LLLT for DED. Study selection and data extraction were conducted according to pre-specified inclusion and exclusion criteria. Meta-analyses were performed for Ocular Surface Disease Index (OSDI), non-invasive break-up time (NIBUT) and tear meniscus height (TMH). Ten clinical studies were eligible for our systematic review, which included a total of 473 participants. Irradiation protocols included treatment sessions using wavelengths of 625-640 nm and/or 810-850 nm, with each session lasting a minimum of 10 min. In our meta-analyses, LLLT monotherapy was associated with significant improvements in OSDI (weighted mean difference [WMD] -11.42, p < 0.00001), NIBUT (WMD +1.49 s, p = 0.005), and TMH (WMD +0.04 mm, p = 0.007). Sensitivity analyses restricted to eligible RCTs confirmed significant effects on OSDI and NIBUT, but not on TMH. No adverse events were reported. LLLT appears to be well tolerated and may improve signs and symptoms of DED, particularly ocular discomfort. It may represent a promising standalone treatment option for patients in whom combination regimens involving IPL treatment are contraindicated.