Light Masks Safe, But Ultimately Ineffective for Non-Center-Involving DME

Sobha Sivaprasad,

MBBS, MS, DM, FRCS, FRCOphth

A recent study has determined that there is no evidence that long-term use of organic light-emitting sleep masks, such as the Noctura 400 Sleep Mask, reduces disease progression rates for patients with diabetic retinopathy (DR) and early diabetic macular edema (DME).

The CLEOPATRA study, led by Sobha Sivaprasad, MBBS, MS, DM, FRCS, FRCOphth with the National Institute for Health Research Biomedical Research Center at Moor Fields Eye Hospital in London, assessed the 24-month efficacy and safety of the use of light mask devices for the treatment and prevention of non-center-involving DME. The team determined that although there are no serious adverse events (SAEs) associated with the treatment, there is also no clear evidence that the use of light masks has any long-term therapeutic benefit for users.

Organic light-emitting sleep masks were developed, according to Sivaprasad and colleagues, around the theory that exposing rod photoreceptors to constant low-level (500-505 nm) light through a patient's eyelids might reduce the risk of hypoxia, which can accelerate microvascular changes during dark adaptation.

In early proof-of-concept tests of chemiluminescent and LED (light-emitting diodes) light masks, some patients showed improvement in retinal function, microaneurysm count, and decreases in retinal thickness. The CLEOPATRA research team expanded on those earlier trials to determine the long-term effectiveness, safety, and compliance of light mask use. The group was particularly interested in the effectiveness of center-involving DME in order to determine whether the light-mask could serve as a less invasive treatment option for patients than the use of anti-VEGF agents, or be used as an adjunct therapy alongside pharmaceutical intervention.

The phase 3, single-blind, parallel-group, randomized multi-center control trial took place at 15 UK National Health Service ophthalmic centers and included patients over 18 years of age with diabetes mellitus (type 1 or 2) and OCT evidence of retinal thickening in at least 1 non-central Early Treatment Diabetic Retinopathy Study (ETDRS) zone as a result of DME. They were randomized 1:1 to either the Noctura 400 Sleep Mask (n = 144) or a sham mask (n = 133) for a 24-month period.

The Noctura 400 Sleep Mask “is designed to deliver blue-green light through closed eyelids,” Sivaprasad explained, via LEDs inserted in the mask's fabric which deliver 75 photopic cd/m² (± 10%), equating to 186 scotopic cd/m² of light over 8 hours while the patients sleep.

This level of light emission was anticipated to cause a 40% reduction in rod-circulating currant without causing any significant change to circadian rhythms, resulting from a >1% change in the melatonin cycle. In order to confirm patient compliance with the use of the light masks, the light masks were designed to automatically record whether they were being worn. For purposes of the study, compliance was defined as 70% of the time for more than 6 hrs/day.

Patient HbA1c levels and refracted BCVA were recorded at baseline, 12- and 24- months, and OCT assessments to determine changes to retinal thickness were performed every 4 months, and twice at 12- and 24- months. Sivaprasad and colleagues also recorded data on patient diabetic medication and interventions, as well as all adverse events during the 24-month period.

Sivaprasad and colleagues reported that “the change in maximum retinal thickness did not differ between treatment groups ((mean change —9·2 μm [SE 2·5] for the light mask vs. –12·9 μm [SE 2·9] for the sham mask)” and that median patient compliance with wearing the light mask for the full 24 months was a low 19.5%, reducing rapidly after the first 6 months of the study.

Although the patients experienced very few AEs with use of the mask, such as discomfort on the eyes (14 with light mask vs. 7 with sham), painful, sticky, or watery eyes (14 vs. 6), and sleep disturbance (7 vs. 1), there were no SAEs associated with mask use.

Ultimately, Sivaprasad and colleagues reported that the use of the light-emitting mask, while safe, “did not confer long term-therapeutic benefit on non-center-involving” DME.

Sivaprasad noted that the results reveal that the light mask is not effective and that variables between the treatment groups showed no significant changes demonstrating treatment effectiveness. Although there was some evidence that the light-emitting masks did reduce diffuse DME and visible cysts in ETDRS zones at 12 months, the changes were not long lasting, which suggests “that any positive morphological effects of these light masks” on DME is “transient and minimal” even in those patients with the highest compliance rates, Sivaprasad wrote.

The study, "Clinical efficacy and safety of a light mask for prevention of dark adaptation in treating and preventing progression of early diabetic macular oedema at 24 months (CLEOPATRA): a multicentre, phase 3, randomised controlled trial" was published in The Lancet.