Retinopathy in diabetes
What is retinopathy?
Retinopathy is the word used to describe non-inflammatory impairment of the retina — the light-sensitive layer at the back of the eye which transmits signals to the optic nerve, allowing us to see.
Diabetic retinopathy
Diabetic retinopathy occurs when the small blood vessels in the retina become swollen, often leaking fluid, haemorrhaging (bleeding) and becoming blocked. This process can cause an overgrowth of new tiny blood vessels that can be associated with scar tissue and retinal detachment (separation of the retina from where it is normally attached to the inside of the eye).
Diabetic retinopathy is a leading cause of blindness and visual disability. People with diabetes mellitus should have regular eye tests to help recognise the condition as early as possible.
Who is at risk of diabetic retinopathy?
This condition generally affects people who have had diabetes long-term (that is, for at least 5 years) to a greater or lesser extent, and fortunately only a small proportion of patients will lose their sight completely. About 50 per cent of people with diabetes will develop some degree of retinopathy after 10 years of diabetes while 80 per cent have retinopathy after 15 years of the disease.
The risk of developing diabetic retinopathy, and the rate of its progression, can be reduced by good blood sugar control.
Changes that may be seen on eye examination
- Microaneurysms: these are the first clinical abnormality to be noticed. They appear as tiny, dark red spots in the light-sensitive retina at the back of the eye. They look like tiny haemorrhages within the retina.
- Haemorrhages: depending on the level of the retina where they occur they may appear as dot, ‘blot’ (round-shaped) or flame-shaped haemorrhages.
- Hard exudates: these are one of the main characteristics of diabetic retinopathy and can vary in size from tiny specks to large patches. As well as blood, fluid that is rich in fat and protein is contained in the eye and this is what leaks out to form the exudates. These can impair vision by preventing light from reaching the retina.
- Soft exudates: these are often called ‘cotton wool spots’ and are more often seen in advanced retinopathy.
Additionally, new tiny blood vessels may form across the retina (neovascularisation). These blood vessels are extremely fragile and may break and bleed easily, resulting in the formation of fibrous (scar) tissue around them. This causes the vision to be obscured and may ultimately cause retinal detachment (where scar tissue pulls the retina away from where it should be). This often causes the sudden loss of sight in one eye. If this happens you must seek help as fast as possible as surgery may be possible to re-attach the retina.
Symptoms of diabetic retinopathy
During the early stages of diabetic retinopathy, there are often no symptoms.
As diabetic retinopathy becomes more advanced, you can experience blurred, distorted or patchy vision that can't be corrected with prescription glasses.
When total blindness occurs it is usually because of a sudden massive haemorrhage in the eye. However, this rarely happens rapidly and in most cases loss of vision will be a slowly progressive process.
Treatment
The treatment for retinopathy is usually a form of laser treatment called panretinal laser photocoagulation, which is normally done under local anaesthetic. In this form of laser treatment, bursts of a laser beam directed at the retina can help stop the growth of the new, abnormal blood vessels, and reduce the risk of bleeding, scarring and retinal detachment occurring. It can reduce the risk of severe visual loss significantly if treatment is undertaken early. This type of photocoagulation is not usually able to restore vision that has already been lost.
It is also very important to maintain good control of your blood pressure and blood sugar levels, as well as keeping your cholesterol in the normal range. These measures can slow down the progression of retinopathy and help preserve your vision.
Other diabetic eye diseases
Patients with diabetes also have a higher risk of developing cataracts (cloudiness in the lens of the eye which leads to vision loss), and glaucoma (a condition where increased pressure within the eye causes impaired vision or even blindness). As well as senile cataracts, which are seen in elderly diabetic patients, young patients with poorly controlled diabetes can develop cataracts and glaucoma.
Last Reviewed: 12 February 2007
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