Obstructive sleep apnoea and retinal vascular reactivity
Research type
Research Study
Full title
Effect of obstructive sleep apnoea on retinal vasculature reactivity following CPAP withdrawal
IRAS ID
149068
Contact name
John Stradling
Contact email
Research summary
Obstructive sleep apnoea is a common condition that has a variety of consequences. It is caused by the back of mouth collapsing intermittently during sleep which can temporarily stop breathing(an apnoea). Patients are often sleepy in the daytime and are offered treatment with a breathing mask (CPAP). CPAP blows air on the back of the mouth during sleep to stop it collapsing.
Diabetic sleep apnoea patients have more patients with problems with the retina than diabetic patients without sleep apnoea. We are looking at non-diabetic patients to see if there are changes in their eyes both with and without CPAP treatment that may help us understand why this happens.
We will look at patients with obstructive sleep apnoea who have been on CPAP treatment for over 12 months who do not have diabetes.
Participants will initially sleep wearing a wrist watch like device overnight (pulse oximeter) with and without their CPAP. Following this they will then be loaned a trial CPAP machine. This will either deliver normal CPAP treatment or altered CPAP treatment, delivered by using a CPAP machine which allows sleep apnoea to return. Throughout the trial they will be asked to record blood pressure twice a day on a machine that will be supplied. They will attend an appointment to have blood tests, blood pressure checked and undergo examination using a specialised camera to look at the back of the eye and take measurements. Blood tests, blood pressure and specialist camera measurements will then be repeated after two weeks. At the end of the trial patients will be put back onto their normal treatment.
Patients will be recruited from the University of Birmingham Hospitals sleep clinic. The trial is funded by ResMed and the Research Fellow will be funded from Oxford Radcliffe Hospitals Charitable Fund no. 0189.
Research Summary:
Obstructive sleep apnoea (OSA) is a common condition affecting 1 in 4 adults. OSA causes the throat to close repeatedly overnight leading to loud snoring, pauses in breathing and dips in blood oxygen levels. OSA is treated by a breathing mask therapy called CPAP. CPAP works by blowing air onto the back of the throat during sleep to hold the throat open and to stop OSA.
OSA has been linked with damage to blood vessels leading to conditions like diabetic eye disease and stroke. We sought to determine the short-term effects of OSA on blood vessels in the back of the year.
We did this by enrolling participants with OSA who were well treated on CPAP. We then randomised these participants to either continue CPAP or to use sham CPAP for two weeks. Sham CPAP leads to a rapid return of OSA. We then examined the effect of OSA on the size of the blood vessels at the back of the eye during a flashing light protocol. In healthy eyes blood vessels increase in size in response to flashing light, but in patients with diabetic eye disease and stroke this response is lost.
We enrolled 37 people with OSA, with 19 using sham CPAP for two weeks and 18 continuing on normal CPAP. After two weeks, eye blood vessel responses to a flashing light were no different in the two groups.
This result shows that two weeks of sham CPAP had no effect on eye blood vessel responses to flashing light. This suggests that OSA does not lead to eye damage via impaired eye blood vessel response, at least in the short-term. This is the first randomised study to examine the effects of OSA on eye blood vessel responses.
REC name
South Central - Berkshire Research Ethics Committee
REC reference
14/SC/1235
Date of REC Opinion
10 Oct 2014
REC opinion
Favourable Opinion