Diabetic retinopathy

Suzie Bushby, from Chichester, who was diagnosed with diabetic retinopathy, said: 

What is diabetic retinopathy?

Diabetic retinopathy is a serious, sight-threatening complication of diabetes. It is the most common cause of vision loss for people living with diabetes. The condition is caused by damage to the tiny network of blood vessels that supply oxygen and nutrients to the retina, the light-sensitive tissue at the back of the eye.

Anyone with any type of diabetes (type 1 or type 2) can develop diabetic retinopathy – and their risk will increase the longer they have diabetes. If the condition is left undiagnosed and untreated, it can lead to blindness.

However, it usually takes several years to reach a stage where it could threaten a person’s sight.

In the early stages of diabetic retinopathy, a person will usually not have any noticeable symptoms. The disease may go undetected until it is more advanced. Early diagnosis and treatment of the condition can help reduce or prevent sight loss.

That’s why it is important to attend regular diabetic eye screening appointments – so that any problems can be spotted early and steps taken to help protect vision.

Managing diabetes well is the best way to lower the risk of developing the condition or help stop it from progressing. In the later stages of the disease, treatments, including eye injections and laser surgery, can help stop a person’s vision from getting worse.

Fight for Sight’s goal is to understand more about the processes involved with diabetic retinopathy and develop new treatments – to help save thousands of people from diabetes-related sight loss.

Read 5 FAQs about diabetes and eye health

What causes diabetic retinopathy?

Diabetes affects how the body regulates blood glucose (sugar) levels. If a person’s blood sugar levels are consistently high, their blood vessels throughout the body can become damaged, which can result in serious complications.

Diabetic retinopathy is caused by damage to the tiny network of blood vessels in the retina – the tissue at the back of the eye that converts light into electrical signals.

These signals are then sent to the brain and interpreted into the images that we see. When these blood vessels are damaged, they can get blocked, leak, or grow incorrectly. As a result of these changes, the retina can’t get hold of enough oxygen and nutrients it needs to work properly, leading to sight loss.

Who is at risk of developing diabetic retinopathy?

Anyone with any type of diabetes is at risk of developing diabetic retinopathy. This includes people with type 1, type 2, and gestational diabetes (which can develop during pregnancy).

Not everybody with diabetes develops retinopathy, but the risk of developing the condition is increased if they:

• have had diabetes for a long time
• have persistently high blood sugar levels
• have high blood pressure
• have high cholesterol
• are pregnant
• are of Asian or Afro-Caribbean ethnic background

What are the stages of diabetic retinopathy?

Diabetic retinopathy develops in three main stages over time:

Stage 1: background diabetic retinopathy 

At the earliest stage of the condition, small swellings can be detected in the capillaries (tiny blood vessels) that supply the retina. These changes don’t normally affect a person’s vision, but monitoring them closely is important as they are at increased risk of developing problems in the future. They will be advised about what steps they can take to prevent the problem from getting worse.

Stage 2: Pre-proliferative diabetic retinopathy 

At this stage, more severe and widespread changes are found in the retina, including bleeding into the retina. There is a high risk that a person’s vision could eventually be affected – and they will usually be advised to have more frequent eye screening appointments to check for any changes.

Stage 3: Proliferative diabetic retinopathy 

At this advanced stage of diabetic retinopathy, there is a very high risk of sight loss. A person’s retinal blood vessels will have become severely blocked or damaged. In response, the body begins to produce new blood vessels - but these are often very weak and prone to bleeding, which can cause scarring to form on their retina.

Leaked blood can also block light from reaching the retina, resulting in sight loss. Proliferative diabetic retinopathy can sometimes lead to retinal detachment, where the retina pulls away from the back of the eye. A person will be offered treatment to stabilise their vision, although it is not possible to reverse any sight loss that has already occurred.

What is diabetic maculopathy? 

Diabetic maculopathy is a different type of retinopathy that affects the blood vessels in the macula – a tiny collection of light-sensitive cells at the centre of the retina.

As the macula is responsible for seeing fine details and central vision, macula-related sight loss can have a big impact on quality of life. A person with diabetic maculopathy may need to be monitored more closely or offered treatment to reduce the risk of vision loss.

What are the signs and symptoms of diabetic retinopathy?

Not everybody with diabetes develops retinopathy. But it is one of the most common complications of the condition - and the longer you’ve had diabetes, the greater the chance of developing it. Within 20 years of diagnosis, nearly everyone with diabetes will be affected to some degree.

People whose diabetes is well managed are less likely to develop retinopathy than those whose blood sugar, blood pressure and cholesterol levels are poorly controlled. Those who smoke are at higher risk. 

Proliferative diabetic retinopathy also tends to be more common in people with type 1 diabetes than type 2. And ethnicity can play a role: People of Afro-Caribbean and South Asian heritage are about twice as likely to develop sight-threatening diabetic retinopathy as white Europeans.

What are the signs and symptoms of diabetic retinopathy?

A person’s vision isn’t usually affected during the early stages of diabetic retinopathy. But as the condition worsens, they may start to notice symptoms such as:

• Gradually worsening vision. A person’s vision may become blurred and patchy, and they may have trouble reading or seeing distant objects. These changes may come and go.
• Changes in colour perception. A person may notice that colours aren’t as clear and vibrant as they used to be.
• Shapes and dark spots: They may see an increasing number of floating shapes or dark spots in their field of vision.
• Eye pain or redness. Diabetic retinopathy doesn’t always cause pain but any eye pain and/or redness should be assessed immediately, as it could be a sign of serious complications.
• Difficulty seeing in the dark. It may be harder, or take longer, to adjust vision when a person enters dark or dimly lit conditions.
• Sudden severe sight loss or vision changes. Retinal detachment is a rare complication of diabetic retinopathy, but when it occurs, symptoms can come on suddenly. This may involve a dark ‘curtain’ moving across the field of vision, a sudden dramatic increase in floaters, or seeing flashing lights. Retinal detachment is a medical emergency that should be assessed urgently.

How is diabetic retinopathy diagnosed?

In the UK, everybody with diabetes is offered regular health checks to monitor how well their condition is being managed and pick up any early signs of problems. This includes annual eye examinations (diabetic eye screening) to check for eye problems caused by diabetes.

During a screening appointment, eye drops will be applied to temporarily dilate (widen) the pupils before a special camera is used to take photographs of the back of the eye. Depending on the findings, more regular monitoring may be advised, or people may be referred for further tests and treatment.

Attending these diabetic eye screening appointments is the most effective way to prevent sight loss due to retinopathy. Early detection and treatment can help stop a person from losing their vision.

How is diabetic retinopathy treated?

The treatment of diabetic retinopathy will depend on the severity of the condition. At all stages of the condition, the most important way to prevent further blood vessel damage is by keeping a person’s diabetes under control. Taking steps to maintain their blood sugar levels at target levels can help stop any vision problems from developing or getting worse.

Diabetic retinopathy usually only requires specific treatment when it has reached an advanced stage, and there’s a risk to a person’s vision. The main treatments include:

Eye injections for diabetic retinopathy

Anti-VEGF drugs can be used to treat diabetic maculopathy. These medicines work by preventing new blood vessels from forming at the back of the eyes. Local anaesthetic is used to numb the eye before the treatment is administered using a very fine needle. As well as preventing further damage, anti-VEGF injections may also help reverse sight loss that’s already occurred.

Laser treatment for diabetic retinopathy

Doctors can use laser surgery to treat new blood vessels at the back of the eye. This can help seal and remove these abnormal vessels, preventing them from bleeding. While this treatment can help stop a person’s vision from getting any worse, it will not usually improve their sight. The procedure is usually carried out as an outpatient procedure, with a local anaesthetic used to numb the eyes first.

Steroid implants for diabetic retinopathy

A person with severe diabetic maculopathy may be offered a steroid eye implant if anti-VEGF injections are unsuitable or haven’t worked for them. This is a tiny implant containing a steroid medicine that’s injected into the eye using a special instrument, following a local anaesthetic to numb the eye. It slowly releases the medicine over a few months to reduce swelling in the eye and can help to improve eyesight. As the implant eventually dissolves, it does not need to be removed.

Surgery for diabetic retinopathy

In severe cases of diabetic retinopathy, surgery may be required. This may include surgery to repair a detached retina or vitreoretinal surgery to remove some of the vitreous humour (the clear jelly-like substance that fills the space between the lens and the retina). The latter may be required if a large amount of blood has collected in the eye or there is extensive scar tissue that may lead to blockages or retinal detachment. Surgery is carried out under general anaesthetic and involves a specialist surgeon making a small incision in the eye before removing some of the vitreous humour, removing any scar tissue and using a laser to prevent any further sight loss.

However, these treatments can’t always undo any damage to the retina that’s already occurred. There is also a risk of side effects, which can range from temporary irritation and blurred vision to permanent sight loss.

What can I do to prevent diabetic retinopathy?

The best way to reduce the risk of developing diabetic retinopathy, or stop it from getting worse, is by controlling blood sugar levels, blood pressure and cholesterol levels. This can often be achieved by making healthy lifestyle choices along with taking any prescribed medications.

Things a person with diabetes can do to help keep their eyes healthy include:

• Getting regular physical activity
• Eating a healthy, balanced diet
• Stopping smoking
• Maintaining a healthy weight
• Taking any medications to help control blood sugar levels, blood pressure and cholesterol levels as prescribed
• Attending regular diabetic eye screening appointments
• Telling their doctor about any changes to their sight

What research is underway?

Fight for Sight’s goal is to understand more about the processes that cause diabetic retinopathy and develop new treatments for tackling damage to help save thousands of people from diabetes-related sight loss.

We are working with partners to fund research projects into diabetic retinopathy.

Key areas include understanding more about how diabetes causes blood vessels to become leaky and investigating any detectable changes within the retina that may occur before blood vessel changes develop. Research to develop more effective treatments to prevent and target complications associated with diabetic retinopathy is also underway.

For example, we are currently funding a team at University College London that is investigating the role of a molecule called Galectin-1 in retinal blood vessel disorders. This research could ultimately lead to new treatments that can help slow down sight loss in patients with diabetic retinopathy.

Last update October 2023

Approved by Professor Tim Jackson PhD, FRCOphth, Consultant Ophthalmic Surgeon, King’s College Hospital and Professor of Retinal Research, King’s College London, and by Professor David Simpson, Queen's University Belfast, The Wellcome – Wolfson Institute for Experimental Medicine School of Medicine, Dentistry and Biomedical Sciences