Photobiomodulation With REd vs BluE Light (REBEL)

The use of photobiomodulation or low-level light therapy (LLLT) in the ophthalmic field stemmed from dermatology which has shown impact on skin blood flow and regeneration. There has been a rise in clinical interest with emerging evidence in the benefits of photobiomodulation in managing chronic inflammatory conditions such as dry eye disease including improvements in ocular discomfort symptoms, tear film stability and tear volume. Despite the observed clinical benefits, limited research has been done to compare photobiomodulation utilising different wavelengths, as most research on dry eye disease has focused on red wavelengths. It has been purported that blue wavelengths may disrupt microbial growth while red wavelengths stimulate energy production and hence increase heat in the affected tissues, although research into these differential impacts at the ocular surface and external eye has been limited. Hence, the aim of this exploratory clinical trial is to compare the impact of using LLLT incorporating red versus blue wavelengths on eyelid haemodynamics and microbiome, as well as conventional ocular surface measures of patients with dry eye disease and blepharitis (inflammation of the eyelids). Participants with dry eye disease, oil gland disruption and blepharitis will receive 3 treatments with these LLLT, each separted by 1 week apart, and followed up to 1 month after the final treatment session. Participants will be randomised to either of 3 groups: Red light only group, Red + Blue light group, or a sham treatment group.