This is a complication which occurs when diabetes causes the retina to become damaged. Diabetes is a condition that occurs when the body cannot control blood sugar levels and there are two types of diabetes, type 1 and type 2. Type 1 diabetes develops when an individual cannot produce insulin to control the level of glucose in the blood. Type 2, which is much more common, develops when insufficient insulin is made or the insulin does not function properly, causing blood sugar levels to be abnormal. Retinopathy is a common complication resulting from diabetes and all patients diagnosed with diabetes are advised to have regular eye tests.
The retina is located at the back of the eye and is made of special cells called rods and cones. When light enters into the eye the rays are refracted by the cornea, focused by the lens and projected onto the retina. Information about the image is then sent from the retina to the brain via the optic nerve. Retinopathy is a term used to describe damage to the retina and in most cases it involves damage to the small blood vessels at the side of the retina.
How does diabetes damage the retina?
If diabetes is poorly controlled it can cause damage to the retina, known as retinopathy. Over time high levels of blood glucose can cause damage to the tiny blood vessels, which are located at the side of the retina. This can contribute to a range of different problems affecting the eyes, including:
- Haemorrhages (bleeds from the blood vessels).
- Exudates (fluid leaks from the blood vessels).
- Microaneurysms (dark red dots on the retina).
- Blocked blood vessels, which disrupt blood supply to the retina.
- Development of abnormal blood vessels from damaged vessels.
Symptoms of diabetic retinopathy
In most cases people do not experience symptoms of retinopathy. However, if diabetes is poorly managed the condition can become worse and it may cause a loss of vision and even blindness. Diabetic retinopathy is among the most common causes of blindness in young people in the UK.
Some people do experience symptoms of diabetic retinopathy, including:
- Blurred vision.
- Seeing flashes.
- Seeing floaters (tiny particles which appear to be floating around in the eye).
- Sudden loss of vision (this is rare).
Stages of diabetic retinopathy
Retinopathy can affect different parts of the eye. If the macula (located in the centre of the retina) is affected this tends to be serious. If the peripheral part of the retina is affected this usually causes no symptoms or mild symptoms.
Retinopathy is usually progressive, meaning it tends to get worse over a period of years. Here is listed the diabetic retinopathy stages:
- Background retinopathy: this is usually mild. You may experience small bleeds in the blood vessels and tiny microaneurysms, but your vision will most likely be unaffected.
- Pre-proliferative retinopathy: damage is more widespread than background retinopathy, but new abnormal vessels have not yet started forming.
- Maculopathy: this occurs when the macula is damaged.
- Proliferative retinopathy: at this stage new abnormal blood vessels have begun to develop (known as proliferation) from damaged blood vessels. The new vessels are much more fragile than normal blood vessels and there is a high risk that they could leak or bleed. If the vessels leak or bleed, this causes harm to the retinal cells. It is likely that your vision will be badly affected if you do not have treatment.
If fluid leaks into the macula this can cause macular oedema (inflammation of the macula), which causes vision to become blurred. A macular oedema is treated with laser treatment.
If proliferative retinopathy becomes very serious and a lot of new vessels develop, this can cause severe damage to the retina and scarring, and it may also cause the retina to become detached. If you have high blood pressure, as well as diabetes, the risk of suffering severe retinopathy is higher.
Who is at risk of diabetic retinopathy?
Anyone who has diabetes has a risk of developing diabetic retinopathy, though it tends to affect people with type 1 diabetes more commonly than those with type 2 diabetes. Risk factors include:
- Duration: the longer you have had diabetes the higher the risk you will develop diabetic retinopathy. The condition is rare in people who have had diabetes for less than 5 years, but it is very common among those who have had diabetes for more than 30 years.
- Glucose control: if diabetes is poorly managed, this can increase the risk of diabetic retinopathy.
- High blood pressure: high blood pressure increases the risk of serious diabetic retinopathy and can also speed up symptoms.
- Kidney disease (known as nephropathy).
- Lifestyle factors, including smoking and obesity.
How is diabetic retinopathy diagnosed?
Diabetic retinopathy can be discovered during eye examinations. Your optometrist will examine your eyes and check for signs and symptoms of diabetic retinopathy. If your optometrist notices symptoms you will be referred to an eye specialist (known as an ophthalmologist), who will carry out further tests to confirm a diagnosis and draw up a treatment plan.
Testing for diabetic retinopathy
The NHS runs a diabetic retinopathy screening programme for all patients over the age of 11 with diabetes, which involves annual checks for signs of retinopathy. The tests involve examining the back of the eye (the retina), checking your vision and taking photographs of the retina. During the test drops will be placed in the eyes to dilate the pupils, which allow the optometrist or doctor to see more clearly.
A test called a fluorescein angiogram may also be carried out and involves injecting a coloured dye into a vein in the arm. The dye travels to the eyes via the blood vessels and a camera is then used to detect any abnormalities in the vessels, leakage from vessels or swollen vessels.
If you notice any changes in your vision before you are due to have an eye test, you should see your GP or our optometrist as quickly as possible.
Treating diabetic retinopathy
If you have mild retinopathy you may not need treatment, but your doctor will keep an eye on you to monitor your eyesight and check for signs that the condition has developed. If you have severe retinopathy and new blood vessels have grown (proliferative retinopathy), the most common treatment is laser eye surgery.
Laser treatment works by using intensive laser beams to seal the blood vessels closed, which prevents leaking and bleeding and also stops any more abnormal new vessels forming. It is common for laser treatment to be administered over the course of several sessions. The type of laser treatment will depend on the individual patient. Laser treatment is usually very successful at preventing further harm to the retina; however, it cannot improve sight that has already been lost.
After laser treatment it is common for your sight to be a little blurred, but it should return to normal after a few days.
If the retina has become detached then surgery will be required. An operation may also be recommended if a vessel has leaked blood into the vitreous humour of the eye, which is known as a vitrectomy. This involves making a miniature incision in the eye and removing the vitreous gel that has been contaminated by blood with a special instrument, after which the vitreous gel is then substituted with a salt compound.
Research into treatments for diabetic retinopathy is ongoing.
Preventing diabetic retinopathy
It may not be possible to prevent diabetic retinopathy, but there are things you can do to reduce the risk or slow down the progress of symptoms. These include:
- Maintaining good control of blood glucose levels.
- Adopting a healthy lifestyle.
- Quit smoking (if applicable).
- Keep an eye on your blood pressure and cholesterol levels.