If you have diabetes, it is vital that you have your eyes checked regularly. Damage to the retina at the back of the eye (retinopathy) is a common complication of diabetes. If left untreated, it can become worse and cause some loss of vision, severe sight impairment or total loss of vision in severe cases.

Good control of blood sugar (glucose) and blood pressure slows down the progression of retinopathy. Treatment with a laser, before the retinopathy becomes severe, can often prevent loss of vision.

Diabetic retinopathy affects blood vessels in the light-sensitive tissue called the retina that lines the back of the eye. It is the most common cause of vision loss among people with diabetes and the leading cause of vision impairment and blindness among working-age adults.

What is the retina?

The retina is made up from special cells called rods and cones which line the back of your eyes. Light enters your eye and passes through the lens which focuses the light on to the retina. Messages about what you see are then passed from the cells in the retina to the optic nerve, and on to the brain. Many tiny blood vessels in the retina take oxygen and nutrients to the cells of the retina.

The term retinopathy covers various disorders of the retina, which can affect vision. Retinopathy is usually due to damage to the tiny blood vessels in the retina.

Retinopathy is commonly caused by diabetes but is sometimes caused by other diseases such as very high blood pressure (hypertension).

Note: people with diabetes also have a higher risk of developing other eye problems, including cataracts and glaucoma.

How does Diabetic Retinotherapy occur?

Over several years, a high blood sugar (glucose) level can weaken and damage the tiny blood vessels in the retina. This can result in various problems which include:

  • Small blow-out swellings of blood vessels (microaneurysms).
  • Small leaks of fluid from damaged blood vessels (exudates).
  • Small bleeds from damaged blood vessels (haemorrhages).
  • Blood vessels may just become blocked. This can cut off the blood and oxygen supply to small sections of the retina.
  • New abnormal blood vessels may grow from damaged blood vessels. This is called proliferative retinopathy. These new vessels are delicate and can bleed easily.

The leaks of fluid, bleeds and blocked blood vessels may damage the cells of the retina. In some severe cases, damaged blood vessels bleed into the jelly-like centre of the eye (the vitreous humour). This can also affect vision by blocking light rays going to the retina.

Retinopathy is a common complication of diabetes. It is more common in people with type 1 diabetes.

Risk factors for diabetic retinopathy include:

  • Duration of diabetes. The longer you have had diabetes, the higher your risk of developing retinopathy. It is uncommon if you have had diabetes for less than five years. However, around 9 in 10 people who have had diabetes for longer than 30 years can be affected.
  • Poor blood sugar (glucose) control. Studies have shown that those people with poor control of their diabetes are more likely to develop all complications, including retinopathy. However, one large study has shown that even a proportion of people who have very well controlled glucose levels still develop diabetic retinopathy in the future.
  • High blood pressure (hypertension). If your blood pressure is not well controlled then this will increase your risk of developing retinopathy.
  • Kidney disease (nephropathy). Having kidney disease as a result of your diabetes is associated with worsening retinopathy.
  • Pregnancy. Being pregnant may make retinopathy worsen, especially if your blood glucose is poorly controlled.
  • Other risk factors include smoking, obesity and having a high cholesterol level..

Laser treatment
Laser treatment is used mainly if you have new vessels growing (proliferative retinopathy), or if any type of retinopathy is affecting the macula. A laser is a very bright light that is very focused so it makes tiny burns on whatever it is focused on. A burn can seal leaks from blood vessels, and stop new vessels from growing further. The burns are so tiny and accurate that they can treat a tiny abnormal blood vessel. Several hundred burns may be needed to treat retinopathy.

There are different types of lasers. The type chosen may depend upon your actual eye condition. It is common to need several treatment sessions.

Treatment usually works well to prevent retinopathy from getting worse, and so often prevents loss of vision. However, laser treatment cannot restore vision that is already lost.

You may find after your laser treatment that your sight may become dim or blurred. This normally improves over the following few days.

Other treatments
Various eye operations may be needed if you have a bleed into the jelly-like centre of the eye (the vitreous humour) or develop a detached retina. These are possible consequences of severe retinopathy. An operation may also occasionally be needed if your laser treatment has not been successful.

The treatment of diabetic retinopathy is a developing area of medicine. Some studies have shown benefits with various newer treatments. (See ‘Further reading & references’ at the end for details.) However, these are not yet widely available and further research is needed to determine their place in the treatment of diabetic retinopathy.