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.

This study will be a randomized, double-masked, exploratory clinical study to assess the potential difference in impact between the two wavelengths used for LLLT. The whole study involves a total of 4 visits (consisting of 3 treatment visits, and 1 follow-up visit). All visits will be conducted at the Aston Dry Eye Clinic in Aston University, Birmingham, United Kingdom.

Eligibility Criteria:
Inclusion Criteria:

* Individuals with dry eye disease symptoms (Ocular Surface Disease Index questionnaire (OSDI) score ≥ 13 or Dry Eye Questionnaire (DEQ5) score \> 6) and signs (tear film instability measured with non-invasive tear break-up time \< 10 s or ocular surface damage measured using special dyes placed on the front surface of the eyes that temporarily stains any aggravated or damaged cells: \> 5 corneal spots, \> 9 conjunctival spots or lid margin staining ≥ 2mm in length and ≥ 25% in width)
* Individuals need to also have Meibomian gland dysfunction. The diagnosis of Meibomian gland dysfunction depends on how many of 5 glands in the central lower eyelid can express oil, and the quality of the oil. A diagnosis is made if there is decreased expressibility (grade 1-3 on the Pflugfelder scale) and reduced quality of oil (grade 1-3 on Bron scale). Any presence of gland blockage and/or loss of oil glands grade 1 to grade 4 of either eyelid \[Pult and Reide-Pult, 2013\]) will also justify a diagnosis of Meibomian gland dysfunction.
* Individuals will also need to have ocular demodicosis, diagnosed by clinical observation on slit lamp biomicroscope based on signs including collarettes around the base of lashes, visible Demodex tails, or excessive pouting of lash follicles in those with good lid hygiene where Demodex was confirmed by secondary means such as visible Demodex tails.
* Age ≥ 18 years, male or female
* Able to provide written consent in English
* Able to attend a total of 4 visits: 3 treatment visits and followed up for 1 month after final treatment

Exclusion Criteria:

* Pregnancy
* Ocular light-based therapies including intense pulsed light (IPL) or LLLT treatment within the past 1 month or during study period in addition to those provided in the study
* Contact lens wear in the past 2 weeks or during study period
* Other active ocular surface diseases or history of ocular surgery or corneal infections the past 6 months