Diabetic Eye Disease
Diabetic retinopathy is an eye disease that's associated with long-standing diabetes. It's a major cause of poor vision in the UK.
Retinopathy can occur with all types of diabetes. If left untreated, diabetic retinopathy can lead to blindness.
The longer a person has diabetes, the higher their chances of developing diabetic retinopathy.
Prolonged periods of high blood sugar levels cause damage to the small blood vessels in the retina at the back of the eye. These blood vessels initially become leaky, and then may become blocked off. This causes haemorrhages (spots of blood) and exudates (proteins) from the blood vessels on to the retina. It may also cause swelling, known as oedema of the retina. The blocked vessels can starve the retina of oxygen, leading to the growth of new abnormal vessels from the retina.
Good control of diabetes by controlling the blood sugar level helps to reduce the chances of developing retinopathy.
It can be classified in different ways, but there are three main types:
These are not different diseases, but are different stages of the same condition. This means the type you have may change as the disease progresses.
This type of retinopathy is not sight-threatening, but needs to be monitored by a doctor who is trained in eye disease (ophthalmologist).
The area of the retina we use most is called the macula. It is essential for clear, detailed vision. In maculopathy, the haemorrhages, exudates and swellings of the first stage occur in the macula. This may interfere with vision, particularly for reading and seeing fine details.
At this stage, some of the tiny blood vessels in the retina become blocked. In response to the lack of blood in the retina, new abnormal blood vessels grow.
These blood vessels are fragile and may:
Both these complications would cause a reduction in vision. If the blood vessels were left untreated, it could eventually lead to blindness.
In addition, the abnormal blood vessels increase the likelihood of a type of glaucoma that is very difficult to treat.
Proliferative retinopathy causes no symptoms until it is very advanced. If a vitreous haemorrhage develops, it can cause sudden loss of vision in one eye.
Diagnosis is made by examining the back of the eye (retina).
Until diabetic retinopathy is at a very advanced stage, vision is not usually affected. This means it's usually detected by routine checks, making regular eye examinations a must for people with diabetes.
Early diagnosis will also help treatment.
Everyone with diabetes should have their eyes examined each year. This may be carried out by the doctor who looks after your diabetes, your GP, or through local programmes that use an optician or diabetic screening eye vans.
If there is any evidence of retinopathy picked up, you will be referred to an eye clinic. The frequency of follow-up then needed depends on the extent of the retinopathy.
There is an increased risk of retinopathy:
This list has some things in common with that for diabetic kidney disease.
Diabetic retinopathy is not entirely preventable, but it's clear that long-term good control of diabetes helps to reduce your risk. You also need to pay attention to the risk factors for heart disease, because they also affect the likelihood of retinopathy. You can do this by:
This requires no treatment, although regular eye examinations are essential.
Often, this doesn't require treatment. Laser treatment is used when the leakage starts to threaten good vision.
While laser treatment may not improve vision, it often prevents deterioration.
When abnormal blood vessels form, laser treatment is used to make the vessels 'regress' or go away.
The laser isn't used on the blood vessels directly, but is scattered over the whole retina (pan retinal photocoagulation).
This destroys the area of retina that is starved of oxygen, eliminating the need for the abnormal vessels.
In rare cases eye surgery is necessary. This may be done:
This type of surgery is called vitrectomy. It involves removing the vitreous (jelly) from the back of the eye. During the process bleeding is also removed.
Laser treatment may be applied at the time of the operation.
If diabetic retinopathy has been diagnosed, and provided it hasn't reached an advanced stage, good control of blood sugar will prevent it from developing further.
So keep your blood sugar level as near normal as possible, and have regular annual check-ups by a hospital diabetologist and ophthalmologist. It's also important your blood pressure is well controlled.
Photographs of the retina can be taken with special cameras and allow detailed examination. Since April 2007 the diabetic retinal screening for Harlow has been carried out by the Basildon & Thurrock Foundation Trust at various times and locations around Harlow and Epping. All diabetics should get an invitation once year to attend a screening session; please contact the Retinal Screening Department on 01268 593811 for further information.