Key takeaways:
- Evidence supports the use of LLLT as a step 2 or 3 therapy for MGD-driven dry eye disease.
- Intense pulsed light appears to have a synergistic effect with LLLT.
Meibomian gland dysfunction is responsible for the majority of dry eye disease cases in clinical practice, yet a substantial proportion of patients achieve only partial and transient relief from conventional first-line therapies.
Warm compresses, lid hygiene, omega-3 supplementation, and topical anti-inflammatory agents remain foundational, but they do not fully address the underlying cellular and glandular pathology driving the disease.
Low-level light therapy (LLLT), a form of photobiomodulation, has emerged as a mechanism-directed, non-pharmacologic modality with a growing evidence base supporting its role in the management of MGD-related dry eye disease (Antwi et al., Chen et al., Chiang et al., de Freitas et al.).
How LLLT works
Photobiomodulation operates through the absorption of low-power red or near-infrared light — typically in the 600 to 1,100 nm wavelength range — by mitochondrial chromophores in target tissues (de Freitas et al.). The primary photoacceptor is cytochrome c oxidase (CCO), the terminal enzyme of the mitochondrial electron transport chain. Under conditions of cellular stress or chronic inflammation, excess nitric oxide competitively inhibits CCO, suppressing electron transport and reducing adenosine triphosphate (ATP) production. LLLT photodissociates this inhibitory nitric oxide from CCO, restoring electron transport chain activity, increasing mitochondrial membrane potential, and upregulating ATP synthesis throughout the cell.