Condition category
Eye Diseases
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
Diabetes is a serious long-term condition where a person is unable to control their blood sugar (glucose). People living with diabetes often have to live with long-term complications of the disease. One of these complications is diabetic retinopathy, where the cells at the back of the eye (the retina) that are sensitive to light become damaged over time. This is because the mechanisms associated with diabetes can affect the oxygen supply to the retina, causing the cells to become starved of oxygen. In order to compensate for this, new blood vessels start to grow behind the retina. These blood vessels are generally very weak and prone to leakage, causing vision to deteriorate. Many of the people who suffer from diabetic retinopathy go on to develop a condition called diabetic macular edema (DME), if left untreated. This is where there is a build-up of fluid, blocking a tiny area in the centre of the retina called the macula, which is responsible for central vision (seeing what is directly ahead). Phototherapy (light therapy) is a type of treatment used to help people suffering from diabetic retinopathy. It works by wearing an eye mask to bed which delivers a precise amount of light into the eyes through closed eyelids (light-emitting sleep mask). This prevents the light-sensitive cells of the retina from adapting to the dark, so that during the night they do not require as much oxygen to work properly, helping to slow down the formation of new, weak blood vessels. The aim of this study is to find out whether wearing a light-emitting sleep mask to bed for 6 months can help to slow down the worsening of DME.

Who can participate?
Adults suffering from DME in either eye, which has caused the macula to swell to at least 220 microns in thickness

What does the study involve?
All participants are given a light-emitting sleep mask to wear every night for eight hours. The eye mask gives off a low intensity, green light which is shone onto closed eyelids during sleep. The eye mask is worn for one month, before it is returned so that the data can be analysed, and a new mask is provided so that the eye masks are worn for a total of 6 months. Participants have eye exams at the start of the study and then after 3 and 6 months to find out if wearing the mask has made any difference to their condition. Participants also complete a questionnaire about their experience of wearing the eye mask and have their blood sugar tested at the end of the study.

What are the possible benefits and risks of participating?
A potential benefit to participants is a significant and meaningful effect by a slowing, halting, or even reversing, of the progression of the patient's retinopathy. The risks of wearing the light mask are small. The light itself is very safe and the mask has undergone significant electrical testing. There does however, remain a small chance that patients could find the masks uncomfortable which may disturb sleep.

Where is the study run from?
Royal Vinohrady Teaching Hospital (Czech Republic)

When is the study starting and how long is it expected to run for?
January 2013 to October 2013

Who is funding the study?
1. Polyphotonix Ltd. (UK)
2. Elon Medical (Czech Republic)

Who is the main contact?
Dr Luke Barclay

Trial website

Contact information



Primary contact

Dr Luke Barclay


Contact details

Discovery 1
TS21 3FH
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Prospective open label clinical trial of a phototherapeutic eye mask for patients with diabetic retinopathy


Study hypothesis

Preventing retinal adaptation to darkness may alter disease progression.

Ethics approval

Ethics committee of Vinohrady Teaching Hospital, 06/02/2013, ref: EK-VP/08/2013 1/2013

Study design

Single-centre prospective open-label non-randomised clinical trial

Primary study design


Secondary study design

Non randomised study

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet.


Diabetic retinopathy


All participants, having been screened and consented, are given a light-emitting sleep mask to be worn each night for 6 months. The masks emit a low intensity, green light (peak wavelength 504±5nm and intensity of 74±10cd/m^2) into their eyes through their closed eyelids for a maximum of 8 hours each night during sleep. The masks last for 1 month, at the end of which time they have to be returned (for analysis) and replaced. Initial and follow-up assessments are carried out at baseline, 3 and 6 months.

Intervention type



Drug names

Primary outcome measure

1. Best corrected visual acuity (VA) is assessed at a distance of 4 metres using ETDRS boards at baseline, 3 and 6 months
2. Macular thickness is assessed by spectral domain optical coherence tomography (OCT) at baseline, 3 and 6 months

Secondary outcome measures

1. Compliance with treatment is assessed by mask usage time (recorded by the masks) after 6 months of use
2. Experience of use is assessed using a questionnaire (specially designed for the purpose of this study) after 6 months of use
3. Control of diabetes is assessed by measuring glycated haemoglobin (HbA1c) at baseline and 6 months

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Aged 18 years or over
2. Diabetic macular edema (DME) greater than 220um (central subfield thickness) in either eye

Participant type


Age group




Target number of participants


Participant exclusion criteria

Patients presenting with significant coneal opacity that precludes OCT and fundus photography.

Recruitment start date


Recruitment end date



Countries of recruitment

Czech Republic

Trial participating centre

Royal Vinohrady Teaching Hospital
Šrobárova 1150/50
Czech Republic

Sponsor information


PolyPhotonix Ltd.

Sponsor details

Discovery 1
TS21 3FH
United Kingdom

Sponsor type




Funder type


Funder name

Polyphotonix Ltd.

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

Elon Medical

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

The investigators and sponsor intend to publish the findings of this trial in a peer reviewed journal.

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

1. 2017 results in (added 18/01/2019)

Publication citations

Additional files

Editorial Notes

18/01/2019: Publication reference added 11/08/2017: Internal review.