The breakthrough that could stop diabetics going blind: Scientists discover mechanism that causes damage to the eyes
By MADLEN DAVIES FOR MAILONLINE
- Scientists have found a way of stopping a common complication of diabetes called diabetic retinopathy, which can cause blindness
- It occurs when high blood sugar levels damage the eye’s retina
- It was previously thought a protein called VEGFC caused the damage
- Scientists found the protein angiopoietin-like 4 also stops eyes functioning
A delicate network of blood vessels supplies the retina with blood. But when these become blocked, leaky or grow haphazardly, the light-sensitive retina becomes damaged and is unable to work properly. The new research found blocking two proteins which trigger the growth of blood vessels could prevent the disease. Currently, treatment for the disease depends on the stage the condition has reached.
In its early stages it can be prevented from getting worse by controlling diabetes. But if it is more advanced, laser surgery or injection therapy to prevent further damage to the eyes may be needed. Laser eye surgery can save central vision, but this often sacrifices peripheral and night vision. Assistant professor of ophthalmology Dr Akrit Sodhi, of the Johns Hopkins University School of Medicine, said several recently developed drugs – bevacizumab, ranibizumab and aflibercept – can help treat these blood vessels.
WHAT IS DIABETIC RETINOPATHY?
Diabetic retinopathy is a common complication of diabetes. It occurs when high blood sugar levels damage the cells at the back of the eye (known as the retina). If it isn’t treated, it can cause blindness. The retina is the light-sensitive layer of cells at the back of the eye. It converts light into electrical signals. The signals are sent to the brain through the optic nerve and the brain interprets them to produce the images that you see. To work effectively, the retina needs a constant supply of blood, which it receives through a network of tiny blood vessels. Over time, a continuously high blood sugar level can cause the blood vessels to narrow, bleed or leak. This damages the retina and stops it from working.
The drugs block the action of VEGF, a protein released in response to low oxygen levels, which stimulates the growth of new, often abnormal, blood vessels. An advanced stage of the disease, in which new blood vessels have grown on the retina. Stopping it from working, is called proliferative retinopathy. But studies have shown that although these drugs slow progression to proliferative retinopathy, they do not reliably prevent it. This suggests VEGF is not the only trigger of new blood vessel growth.
To investigate this, the researchers tested eye fluid samples from healthy people, people with diabetes who did not have diabetic retinopathy and those with diabetic retinopathy of varying severity. While levels of VEGF tended to be higher in those with proliferative diabetic retinopathy, some of their fluid had less VEGF than the healthy participants’.
Source: NHS Choices and Daily Mail