शुक्रवार, 8 अप्रैल 2011

What is diabetic retinopathy?

What is diabetic retinopathy?
Diabetic retinopathy is a sight-threatening long term complication of diabetes. This leaflet explains how
diabetic retinopathy develops, how it can be treated, how its progress can be slowed and why it is important
for people with diabetes to attend regularly for screening.
The specific changes in the eye which develop as a direct effect of raised glucose levels on the small blood
vessels in the part of your eye called the retina are known as diabetic retinopathy. Severe changes to these
retinal blood vessels can damage your sight.
The retina lines the inside of the eye and acts rather like the film in a camera. The macula is the small central
part of the retina you use to see things clearly and is the part you are using now to read this leaflet. The rest of
your retina is used to view the world around you and to see in the dark.
Let’s look at how these changes might affect your vision in more detail.
Background Retinopathy
These are earliest changes. Small swellings develop on the blood vessels and appear as tiny red dots. These are
called microaneurysms. Larger red dots are called retinal haemorrhages. They lie within the retina and are rather
like a bruise on your skin. Background retinopathy will not affect your vision and does not need treatment. See
Figure 1
Proliferative Diabetic Retinopathy
With time, the blood vessels may become progressively constricted, starving the retina of oxygen and nutrition.
Different signs can be seen in the retina during this progression. These changes are called “pre-proliferative
Eventually new blood vessels may develop on the surface of the retina. This is called ‘proliferative diabetic
retinopathy’. See Figure 2 If this happens your sight will be at risk as these new blood vessels may bleed or may
develop scar tissue.
If the new vessels bleed into the jelly (vitreous) inside the eye you may see a sudden shower of floaters or
cobwebs, or your sight may become completely blurred. This is called a ‘vitreous haemorrhage’. You should
contact your GP or an eye department immediately for advice if you experience these symptoms.
The scar tissue can pull the retina away from the underlying nourishing layers of the eye, causing a drop in
vision. A ‘traction retinal detachment’ requires an operation on the eye.
Diabetic Maculopathy
The other way in which your vision may be affected is due to damage to the blood vessels in the macular
region of the retina. This is called ‘diabetic maculopathy’.
The commonest change is that the blood vessels become leaky. Fats and fluid that are normally carried along
in the bloodstream leak into the macula. Fluid leaking causes water-logging in the retina and is called ‘oedema’.
Because the macula is used for detailed vision this will cause progressive blurring of your vision.
Occasionally, the blood vessels in the macula become so constricted that the macula is starved of oxygen and
nutrition. This is called ‘ischaemic maculopathy’ and it does not usually respond to any type of treatment.
Diagnosis and treatment
At present laser treatment is the only proven treatment for sight threatening diabetic retinopathy (STDR). The
aim of laser treatment is to stabilise the changes caused by diabetes. Laser treatment can control but not cure
diabetic retinopathy and it is likely that it will need to be repeated at intervals during a person’s lifetime.
Laser treatment does not generally improve your sight, although in some cases it might. However if the
changes are not treated it is likely that some, or all, of your sight will be lost.
If you have proliferative retinopathy, or your eye specialist thinks you soon may, a large number of laser burns
will be applied to the outer part of the retina, the part of the retina that allows you to see to the side and in the
dark. If given early this treatment is very successful.
If you have leakage in the macula, threatening or affecting your vision, gentle laser burns will be applied to the
leaking areas. Laser treatment prevents serious sight loss in 60-70% of cases of maculopathy.
Many new treatments for diabetic retinopathy are under research at present.
The importance of screening
Untreated diabetic retinopathy is one of the most common causes of blindness in the working-age population.
Laser treatment is very effective at reducing sight loss but only if given at the appropriate stage in the
progression of changes. Unfortunately diabetic retinopathy does not usually affect a person’s sight until the
changes are quite far gone. At this stage, laser treatment is much less effective.
So it is vital that you attend for screening every year!
If problems are detected you will be referred to an ophthalmologist for treatment and follow up.
Other effects of diabetes in the eye
• People with diabetes may occasionally develop double vision due to paralysis of the muscles that control eye
movement .This is usually temporary and resolves by itself.
• There is a relationship between diabetes and the development of open angle glaucoma. Glaucoma is a condition
causing a rise in the pressure within the eye leading to damage to the delicate nerves at the back of the eye. If
untreated this results in loss of vision. Glaucoma is usually treated with eye drops.
• People with diabetes are also at increased risk of developing vascular occlusions in the eyes. This is rather like having
a stroke in the eye. In some circumstances this causes a sudden and dramatic drop in vision. In other cases the vision
is not affected. The risk is higher if the blood pressure is also high. Blood thinning drugs, such as aspirin, reduce the
chance of further attacks.
• Probably the most common other eye condition that people with diabetes develop is cataract. A cataract is
cloudiness of the lens of the eye and leads to progressive blurring of vision. As we get older it is common for all of us,
with and without diabetes, to develop cataract. If a cataract affects your quality of life or prevents a good view of the
retina it can be treated by simple keyhole surgery.
Top tips for healthy eyes
Diabetic retinopathy can get worse over time, but the following measures can help to reduce your risks of
developing diabetic retinopathy and to slow the progress of sight-threatening changes.
• Control your blood glucose as effectively as possible.
• See your doctor regularly to check your blood pressure.
• Keep your regular screening appointment.
• Get advice if you have a problem with your sight.
For your eyes and general health, you should also have your cholesterol levels checked regularly and not smoke.

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