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Diabetic retinopathy

Statistics


UK [1]

  • There are currently over 2.3 million people with diabetes in the UK and there are up to another 750,000 people with diabetes who have the condition and don’t know it
  • Type 1 diabetes is the least common of the two main types and accounts for between 5 – 15% of all people with diabetes
  • Type 2 diabetes usually appears in people over the age of 40, though in South Asian and African-Caribbean people often appears after the age of 25. However, recently, more children are being diagnosed with the condition, some as young as seven
  • Type 2 diabetes is the most common of the two main types and accounts for between 85 - 95% of all people with diabetes


Global [2]

  • Global causes of blindness as a proportion of total blindness in 2002: Diabetic Retinopathy 4.8%


What is diabetic retinopathy?
Diabetes can affect the eye in a number of ways. The most serious eye condition associated with diabetes involves the retina, and, more specifically, the network of blood vessels lying within it.


Background

Estimates suggest that nearly one person in twenty five in the UK is affected by diabetes mellitus, a condition which means that, due to a lack of insulin, the body cannot cope normally with sugar and other carbohydrates in the diet. Diabetes can start in childhood, but more often begins in later life. It can cause complications which affect different parts of the body, the eye being one of them. There are two different types of diabetes mellitus:

Type 1 diabetes - This can also be referred to as insulin dependent diabetes mellitus (IDDM). This type of diabetes commonly occurs before the age of 30 and is the result of the body producing little or no insulin. Type 1 is controlled by insulin injections.

Type 2 diabetes - This can also be referred to as non-insulin dependent diabetes mellitus (NIDDM). This type of diabetes commonly occurs after the age of 40. In this type of diabetes the body does produce some insulin, although the amount is either not sufficient or the body is not able to make proper use of it. This type of diabetes is generally controlled by diet or tablets, although some people in this group will use insulin injections.


Stages
Diabetic retinopathy is usually graded according to how severe it is. The three main stages are:

Background diabetic retinopathy - This condition is very common in people who have had diabetes for a long time. Your vision will be normal with no threat to your sight. At this stage the blood vessels in the retina are only very mildly affected, they may bulge slightly (microaneurysm) and may leak blood (haemorrhages) or fluid (exudates). The macula area of the retina mentioned earlier remains unaffected.

Maculopathy - With time, if the background diabetic retinopathy becomes more severe, the macula area may become involved. This is called maculopathy. If this happens, your central vision will gradually get worse. You may find it difficult to recognise people's faces in the distance or to see detail such as small print. The amount of central vision that is lost varies from person to person. However, the vision that allows you to get around at home and outside (peripheral vision) will be preserved.

  • Maculopathy is the main cause of loss of vision and may occur gradually but progressively
  • It is rare for someone with maculopathy to lose all their sight

Proliferative diabetic retinopathy - As the eye condition progresses, it can sometimes cause the blood vessels in the retina to become blocked. If this happens then new blood vessels form in the eye. This is called proliferative diabetic retinopathy, and is nature's way of trying to repair the damage so that the retina has a new blood supply.

Unfortunately, these new blood vessels are weak. They are also in the wrong place - growing on the surface of the retina and into the vitreous gel. As a result, these blood vessels can bleed very easily and cause scar tissue to form in the eye. The scarring pulls and distorts the retina. When the retina is pulled out of position this is called retinal detachment.

  • Proliferative retinopathy is rarer than background retinopathy
  • The new blood vessels will rarely affect your vision, but their consequences, such as bleeding or retinal detachment may cause your vision to get worse. Visual loss in this case is often sudden and severe
  • Your eyesight may become blurred and patchy as the bleeding obscures part of your vision
  • Without treatment, total loss of vision may happen in proliferative retinopathy
  • With treatment, sight-threatening diabetic problems can be prevented if caught early enough. However, laser treatment will not restore vision already lost


Other effects
Temporary blurring - This may occur as one of the first symptoms of diabetes although it may also occur at any time when your diabetes is not well controlled. It is due to a swelling of the lens of the eye and will clear without treatment soon after the diabetes is brought under control again.

Cataracts - A cataract is a clouding of the lens of the eye, which causes the vision to become blurred or dim because light cannot pass through the clouded lens to the back of the eye. This is a very common eye condition that develops as people get older but someone with diabetes may develop cataracts at an earlier age than someone without diabetes. The treatment for cataracts involves an operation to remove the cloudy lens, which is usually then replaced by a plastic lens, helping the eye to focus properly once again.


Further information



[1] Diabetes UK (n.d.) What is diabetes? [accessed 27/11/12].
[2] World Health Organisation (2004) Magnitude and causes of visual impairment. [accessed 27/11/12].

 



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