Damage to blood vessels in the retina, caused by diabetes mellitus
- Usually occurs in adults who have had diabetes mellitus for many years
- Sometimes runs in families
- Poor control of diabetes mellitus and smoking are risk factors
- Gender is not a significant factor
If you have diabetes mellitus, you have an increased risk of developing retinopathy. Diabetes mellitus can lead to abnormalities in small blood vessels anywhere in the body. If the damage affects vessels in the retina, the light-sensitive membrane at the back of the eye, diabetic retinopathy develops. The condition usually affects both eyes. At first, small blood vessels in the retina leak. Later, fragile new blood vessels may grow out into the jelly-like vitreous humour, a condition known as proliferative retinopathy. Loss of vision may result if retinopathy is left untreated, and blindness may eventually follow.
The longer people have had diabetes and the less tightly the disorder is controlled, the greater the risk. Only a few people with type 1 diabetes mellitus develop retinopathy within the first 10 years after diabetes is diagnosed but, once retinopathy is established, it can progress rapidly. The condition may be present to some extent in type 2 diabetes mellitus by the time the diabetes has been recognized.
What are the symptoms?
Symptoms of diabetic retinopathy may not be noticeable until damage to the retina is severe, although there may be areas of blurred vision. As the disease progresses, vision may suddenly be lost in one eye due to rupture of one of the fragile new blood vessels in the retina (see Vitreous haemorrhage) or the separation of the retina from the underlying tissue (see Retinal detachment). You should consult your doctor immediately if you experience sudden loss of vision.
Everybody over the age of 11 who has diabetes should be registered with their local diabetic retinopathy centre, which arranges for every person to have regular photographs taken of their retina. These photographs are examined for signs of retinopathy so that it can be identified and treated as soon as possible.
What might be done?
Established diabetic retinopathy can be identified by studying the retina with an instrument called an ophthalmoscope (see Ophthalmoscopy). If your doctor suspects early retinopathy, he or she may arrange for fluorescein angiography, in which dye is injected into the circulatory system to show the retinal blood vessels in detail.
In some cases, your doctor may arrange for a diagnostic procedure called optical coherence tomography (OCT). This procedure, which is quick and painless, involves shining a light into the eye and then using the reflections from the back of the eye to produce a cross-sectional image of the retina, in an analogous way to how ultrasound scanning produces images using echoes.
If diabetic retinopathy is detected at an early stage, treatment may not be necessary, although your doctor will recommend regular monitoring. In later stages of the condition, laser surgery (see Laser surgery for retinopathy) will probably be recommended, particularly if you have proliferative retinopathy. Any visual loss due to diabetic retinopathy that has already occurred is usually permanent but laser surgery should prevent further loss of sight, although it may be necessary to have repeat treatments.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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