Diabetes & the Eye

Diabetes is becoming increasingly common and if undetected may lead to irreversible blindness. In this brief article I would like to provide an overview of diabetes, how it affects the eye and what can be done about it. This article is not meant to replace the advice of your GP or eye specialist.

What is diabetes?

Diabetes mellitus is due to a lack of insulin effect, which means that the body cannot cope normally with sugar and other carbohydrates in the diet. There are two forms – Type 1, often called insulin dependent diabetes mellitus (IDDM), commonly occurs before the age of 35 and is the result of the body producing little or no insulin. Type 1 is controlled by insulin injections. Type 2, which can also be referred to as non-insulin dependent diabetes mellitus (NIDDM), 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. Diet or tablets generally control this type of diabetes, although some people will use insulin injections. Estimates suggest that one person in twentyfive in the UK is affected.

How can diabetes affect the eye?

Diabetes affects small calibre blood vessels (veins and arteries) by either causing them to become leaky or to cause narrowing and poor blood flow in them. The retina (a delicate layer at the back of the eye vital for eyesight) is mainly affected, more specifically the network of blood vessels lying within it. In diabetic retinopathy leaky blood vessels cause the retina to become water-logged (“oedema”) and narrowed arteries cause the retina to become starved of nutrients and oxygen (“hypoxia”) which can become so severe that the retina may try to grow new blood vessels but these often bleed heavily inside the eye (“proliferative retinopathy”). Both water-logging and hypoxia can lead to loss of eyesight. In addition the lens inside the eye can become cloudy which is called a cataract.

So what can be done?

As with many medical conditions early detection is the most single most important intervention before irreversible changes in the retina take place. It is imperative that all those with diabetes have their eyes examined at least once a year by an ophthalmologist (eye surgeon). Their training and expertise allow for confident detection, monitoring and if necessary treatment of diabetic retinopathy and cataract. Treatment should involve tight glucose/diabetic control with a low-sugar diet under the auspices of a GP or physician. If eye treatment is required then this usually involves special laser treatments to the retina to stabilise the condition. Newer treatments by way of ocular injections are proving very successful in some select patients. Surgery may also rarely be needed.

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