Diabetes and your sight - what you need to know
Did you know that almost one in 25 people in the UK have diabetes? It occurs when our bodies can't produce enough insulin, or when the insulin produced can't be used properly by the body. Insulin is a hormone which regulates how our bodies use food, and diabetics may need to rely on insulin tablets or injections for the rest of their lives.
Smoking, a sedentary lifestyle and obesity are all risk factors for developing diabetes, and whilst it can affect children, it is more common to develop the condition as you get older. As well as the obvious impact on your life – having to control your blood glucose levels and watch what you eat – diabetes can also affect your eyes.
What's the difference between type 1 and type 2 diabetes?
Both type 1 and type 2 diabetes can impact your vision – here's the difference between the two:
- Type 1 diabetes most commonly affects people before they reach the age of 30. With this type of diabetes, the body doesn't produce any (or produces little) insulin. It's also known as insulin dependent diabetes, as it is usually controlled with insulin injections
- Type 2 diabetes usually affects people over the age of 40, and it occurs when the body produces an insufficient amount of insulin, or when the body can't properly use the insulin produced. This type of diabetes is usually controlled with diet and exercise, although tablets are also used. Some people use insulin injections, but it's less common than with type 1 diabetes.
How your eye works
In order to understand how diabetes can affect your eyes, you first need to know how your eye works. Light passes through the front of the eye and the cornea and lens focus it onto the retina, a delicate, light-sensitive tissue. The retina converts this light into electrical signals which are sent along the optic nerve to your brain, allowing you to see. The retina relies on blood supply from a network of blood vessels, which can be damaged by diabetes.
When light enters the eye, it focuses on an area known as the macula, in the centre of the retina. This area is tiny yet vital to detailed vision – it's responsible for allowing us to view fine detail, such as writing in a book, or someone's facial features, and also allows us to recognise colours. The remainder of the retina is responsible for peripheral vision.
How does diabetes affect your eyes?
There are a number of ways in which your eyes can be affected by diabetes – many of these can progressively worsen with time, so it's important to see your GP if you notice any changes in your vision.
- Diabetic retinopathy occurs when the network of blood vessels supplying the retina are damaged
- Long-term effects can cause cataracts, where the lens of the eye turns cloudy
- Blood sugar level changes can affect the lens, which could cause on-and-off blurring of vision
What is diabetic retinopathy?
It sounds serious, and it is. In fact, diabetic retinopathy is the most serious complication of diabetes affecting your eyes. If you suffer from diabetes, the tiny blood vessels in your eye could leak or become blocked, affecting your retina. It's estimated that around 40% of type 1 diabetes sufferers and 20% of type 2 sufferers will go on to develop some form of diabetic retinopathy.
There are several different degrees of diabetic retinopathy, the most common being background diabetic retinopathy. This condition only mildly affects the retina's blood vessels, which could bulge, leak fluid or haemorrhage. With this type of diabetic retinopathy, vision usually remains normal, but you should still mention your symptoms to your GP or at your regular retinal screening. If your retinopathy worsens, you may be unable to see properly, drive or be independent.
If left unchecked, background diabetic retinopathy could progress to:
- Proliferative diabetic retinopathy – With this condition, the blood vessels supplying oxygen to the retina become blocked, causing oxygen-deprivation. New blood vessels could start to grow on the retina's surface, and due to their delicate nature, they could burst, causing large areas of haemorrhaging and obscuring vision in the affected eye. This could lead to permanent loss of sight. Proliferative diabetic retinopathy affects between 5 to 10% of all people with diabetes
- Diabetic maculopathy – With this condition, the macula is affected and you may find you struggle to see fine detail such as small print, losing some of your central vision. This condition can be treated with injections or a laser, to prevent further sight loss
How to protect your eyes
If you have been diagnosed with type 1 or type 2 diabetes, it is important to control your diabetes to reduce your risk of developing retinopathy. Here are a few things you can do to lower your risk:
- Control your blood pressure
- Keep your cholesterol levels in check
- Control blood sugar levels
- Stay fit, maintain a healthy weight and quit smoking – smoking can increase your risk of nerve damage and cardiovascular disease if you have diabetes and can also raise your blood glucose level and blood pressure, making diabetes harder to control
- Attend regular retinal screening – your GP will usually arrange an annual check-up at a specialist screening centre, where eye drops will be put into your eyes and a photograph is taken with a digital retinal camera. With regular retinal screening, 90% of blindness in diabetes sufferers can be avoided.