A Comparative Study on the Efficacy of Blue Light versus Red Light in Alleviating Symptoms of Dry Eye

To identify the level of efficacy between low-level blue light therapy and red-light therapy in reducing symptoms and signs of a dry eye disease (DED) linked to dysfunction of the meibomian glands (MGD) in the first place. This is a prospective, random, blind, parallel group clinical trial that recruited 96 adults (mean age 45 +12 years old) with mild-to-moderate DED (OSDI 13 +10 seconds TBUT). The participants were assigned to a random trial (1: 1) to administer low-level light therapy (LLLT) with two sessions per week, with a 4-week duration (8 sessions): blue light (415-495 nm) or red light (620-750 nm) with a fixed irradiance. Change in baseline and week 4 Ocular Surface Disease Index (OSDI) was the primary outcome. Secondary outcomes consisted of noninvasive tear break-up time (NITBUT), tear meniscus height (TMH), lipid layer thickness, and safety parameters that were measured at baseline, week 4, and week 12. Both treatments were significant (p < 0.001 between groups) in improving symptoms and signs. Red light performed better than blue light in reducing OSDI (37.8 = 11.9 to 16.1 = 8.5) and (38.2 = 12.4 to 22.8 = 9.5), respectively; between-group p < 0.001). Red light also showed better gains in NITBUT (+4.8 vs. +2.9 seconds, p = 0.004), lipid layer thickness (+24 vs. +9 nm, p < 0.001), and TMH. Blue light had no significant improvement, especially in a subgroup of blepharitis. There were no severe negative incidents. Red light LLLT is better and more effective than blue light in relieving DED caused by MGD, probably because it has better photobiomodulation of meibomian glands. There is the possibility that blue light has an adjunctive antimicrobial role. The results suggest that red light is a better standalone wavelength for light-based DED management.