Keeping sight of the costs by heading off threat of diabetic eye disease

MEDICAL MATTERS: "I would rather, I would rather go blind boy
Than to see you walk away from me, child" Etta James 1967

These lyrics from the blues classic I’d rather go blind are a reference to strong feelings of love in the song. But it’s fair to say they do not represent the wishes of the 190,000 people with diabetes in Ireland, for whom one of the disease’s complications is the threat of the eye disease diabetic retinopathy.

Eye disease is one of the long-term complications of diabetes. Both glaucoma and a condition called retinopathy occur in people with diabetes. Retinopathy means disease of the retina, the camera-like structure at the back of the eye. It records the images we see and converts these into electrical signals which are sent to the brain for interpretation.

Within the retina there is an area called the macula, which specialises in seeing fine detail. The back of the retina is full of small blood vessels (capillaries).

Retina damage

In diabetic retinopathy, the retina can be damaged in two ways: non-proliferative and proliferative. In non-proliferative retinopathy, the most common form of retinopathy, capillaries in the back of the eye balloon and form pouches.

As the disease progresses, more blood vessels become blocked; eventually fluid leaks into the macula causing blurred vision. Macular oedema can be treated successfully. But proliferative retinopathy is more serious: in this form the blood vessels close off and new vessels start to grow in their place. The new vessels are weak and leak blood easily causing haemorrhage and blocking vision.

They may also precipitate new scar tissue leading to detachment of the retina and sight loss.

Both forms of retinopathy rarely cause symptoms, meaning the only way to pick up the problem is by regular eye-screening of people with diabetes.

The success of screening is illustrated in a research paper in the current issue of the British Journal of General Practice. In 2011, GP practices in the south of Ireland, members of the Diabetes in General Practice group, invited some 3,600 adults with diabetes to participate in free retinopathy screening provided by community optometrists and community ophthalmologists.

After six months about half of those invited had been screened. Just short of 400 patients were found to have some degree of retinopathy, while six people were newly diagnosed with the severe, sight-threatening form of the disease.

“That represents about one in 250 people screened,” said Dr Diarmuid Quinlan, one of the authors of the paper. “Without treatment approximately 90 per cent of these will lose vision within five years. With treatment, about 90 per cent do not lose their vision.”

Increase of 120 per cent

In Ireland, the incidence of blindness among people with diabetes is not known. However, a study conducted in 2003 using data from the National Council of the Blind found an increase of 120 per cent in the numbers registered as blind as a result of diabetic retinopathy, between 1996 and 2003, suggesting a rate of 10.7 per 100,000 adults in 2003.

How is diabetic retinopathy treated? In photocoagulation, the eye specialist makes tiny burns on the retina with a special laser. These burns seal the blood vessels and stop them from growing and leaking.

This technique is used early in the disease but if a lot of blood has leaked into the eye then a surgical operation – vitrectomy – may be needed.

The bottom line for a cash-strapped health service is that the cost of treating patients with diabetes complications is almost four times the cost of looking after them before complications such as diabetic retinopathy set in.

The Cork study has shown it can be done effectively in Ireland; all that is needed now is a final push to implement a 2009 promise to commence a national screening programme for diabetic eye disease here.

The human costs of not doing so are unquantifiable.

mhouston@irishtimes.com

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