What you need to know about diabetic retinopathy

Over four million people in the UK have diabetes and over half of people living with diabetes will develop a complication called diabetic retinopathy. It is caused by damage to the back part of the eye called the retina, which leads to reduced vision and, if left untreated, permanent vision loss.

How does diabetes affect the retina?

Your retina acts like a camera film by capturing visual information that passes into your eye and sending it to your brain, where it is processed. It is supplied by a network of blood vessels. These blood vessels can become weak and leaky in diabetes due to persistently high blood sugar (glucose) levels. 

As blood leaks out of these blood vessels, the retina becomes damaged. This leads to poorer vision and can cause complete vision loss if left untreated. 

Are you at risk of diabetic retinopathy?

If you have diabetes, you are at risk of developing diabetic retinopathy. Your risk increases the longer you have diabetes and the greater the severity of your diabetes. 

Consequently, if you develop diabetes at a younger age, your lifetime risk of diabetic retinopathy is higher. As type 1 diabetes tends to occur at a younger age, this condition is linked to a higher risk of diabetic retinopathy. 

For individuals with type 2 diabetes, which tends to develop over a longer period of time than type 1 diabetes, early signs of diabetic retinopathy may already be present when an individual is diagnosed with type 2 diabetes.

Other risk factors for developing diabetic retinopathy include poor control of your blood sugar levels, a family history of the condition, high cholesterol, high blood pressure, smoking and being of South Asian, Afro-Caribbean or African descent. 

Long-term steroid use also increases your risk as this medication can cause spikes in your blood sugar levels. 

If you are pregnant and develop gestational diabetes, you are at risk of diabetic retinopathy too. 

Symptoms of diabetic retinopathy

Diabetic retinopathy often doesn’t present any symptoms in the early stages ie it is asymptomatic. This is why, in the UK, all individuals aged 12 and over with diabetes are eligible for free eye screening every year to check for vision changes as part of the NHS Diabetic Eye Screening Programme.

As diabetic retinopathy progresses, you may notice a gradual reduction in your vision, or your optometrist or ophthalmologist (a doctor who specialises in treating the eye) may notice changes in the appearance of your retina. 

Other symptoms of diabetic retinopathy include patchy or blurred vision, eye pain or redness (if abnormal blood vessels are growing), and dark floating spots or cobweb-like streaks in your vision (floaters). 

There are several different reasons why floaters can develop in your vision. In the case of diabetic retinopathy, they are caused by blood vessels that supply your retina leaking into the gel-like fluid that fills the space between your lens and retina (vitreous fluid).

Stages of diabetic retinopathy

Diabetic retinopathy can be divided into three stages. 

Stage 1 is called background retinopathy, where small bulges called microaneurysms can be seen in the blood vessels supplying your retina. These microaneurysms may leak small amounts of blood.

Stage 2 is called pre-proliferative retinopathy, where more significant changes occur across your retina. This includes greater swelling of your blood vessels such that the blood supply to parts of your retina is reduced. This can lead to blurred vision as fluid builds up in the central part of your retina (macula), which is needed for clear vision. 

Stage 3 is called proliferative retinopathy, where some of the blood vessels supplying your retina are blocked. This triggers your body to grow new blood vessels; however, this growth causes further damage to your retina as these new blood vessels are weak and leak more blood. 

An increased build-up of fluid caused by more leaky blood vessels can cause your retina to become waterlogged. If this occurs in the macula part of your retina (ie the part needed for reading), it leads to a loss of vision and you will need injections (called anti-VEGF injections) to improve this. 

Getting a diagnosis 

Routine eye test

Diabetic retinopathy is often diagnosed at a routine eye check-up at your opticians. This usually involves using a slit lamp, where you position your head against a forehead support and chinrest, and a bright light is shone into your eyes to allow your optician to examine your retinas.

Most opticians also offer OCT (optical coherence tomography) scanning. This is a useful tool to detect early changes in your retina, such as those that occur during diabetic retinopathy. An OCT scan takes less than a minute and involves passing a beam of light through your retina to create a detailed 3D image of its layers. 

Diabetic eye screening

If you have been diagnosed with diabetes, it is important to attend your annual diabetic eye screening test. As part of this test, you will be asked to read letters on a chart. 

You will also have your retinas examined using digital retinal photography. First, you will be given eye drops to widen (dilate) your pupils. You will then position your head against a forehead support and chinrest. Next, a camera will take photos of your retinas, one eye at a time. 

Fluorescein angiography

If you are under the care of an ophthalmologist or have been referred to an ophthalmologist by your optician or GP, they may perform a fluorescein angiogram. 

During a fluorescein angiogram, you will be given eye drops to dilate your pupils. Then, a yellow dye called fluorescein will be injected into a vein in your hand or arm. The dye will flow through your blood vessels, including those that supply your retinas. 

Finally, a special camera will take photos of your retinas — the fluorescein will make it easier for your ophthalmologist to spot any leaky blood vessels from these photos. 

Treatments for diabetic retinopathy

Treatment for diabetic retinopathy depends on how far the condition has progressed. In stages 1 and 2, close monitoring and improved control of your blood sugar levels can help prevent your condition from progressing.

In stage 3, your ophthalmologist may recommend laser treatment or eye injections — if you drive and need regular treatment, you will need to tell the DVLA.

Laser treatment

This targets the new, weak blood vessels that have developed in your retinas to prevent blood flowing through them. This helps reduce the amount that these blood vessels can leak. 

Eye injections 

This involves injecting a medication that blocks the activity of a protein called VEGF (vascular endothelial growth factor). VEGF stimulates the production of new blood vessels; anti-VEGF injections, therefore, prevent the growth of new blood vessels and reduce the build-up of fluid in your eyes. 

Steroid implants

If anti-VEGF injections aren’t effective or aren’t suitable in your case, your ophthalmologist may recommend steroid implants. This involves injecting a tiny implant containing the steroid dexamethasone into the vitreous of your eye, close to your retina. The steroid is slowly released over several months and helps reduce the build-up of fluid and swelling in your eye. 

Complications of diabetic retinopathy

Diabetic retinopathy increases your risk of developing cataracts — clouding of the lenses in your eyes — earlier in life. It also increases your risk of glaucoma (high pressure in your eyes), as well as other vision-threatening eye conditions such as macular oedema and retinal bleeding. 

Left untreated, diabetic retinopathy can cause permanent vision loss. However, with treatment further vision loss can be prevented and, in some cases, lost vision can be regained.

As diabetic retinopathy is a disease of small blood vessels, if you have this condition, you are also more likely to develop other conditions caused by damage to blood vessels from diabetes eg heart disease, stroke and kidney disease.

How to reduce your risk of diabetic retinopathy

If you have diabetes, it is important to keep up with your regular eye check-ups, annual eye screening and diabetes check-ups.

You can significantly reduce your risk of diabetic retinopathy by consistently controlling your blood sugar levels and ensuring your cholesterol and blood pressure are within healthy limits. 

Consequently, it is important to maintain a healthy weight, quit smoking and limit how much alcohol you drink or quit drinking alcohol as it can cause spikes in your blood sugar levels.