Diabetic eye disease

What is diabetic eye disease?

Diabetic eye disease is the name for a group of eye problems that can develop if you have type 1 or type 2 diabetes, including retinopathy, macular oedema, cataracts and glaucoma. Retinopathy, the best known of these, happens when high blood sugar levels damage the tiny blood vessels at the back of your eye, usually over several years.

What are the symptoms of diabetic eye disease?

In the early stages, diabetic eye disease often causes no symptoms at all. This is one reason it's usually picked up at a screening appointment, before you'd notice any change to your sight yourself.

As it progresses, you may notice:

• your eyesight gradually getting worse
• blurred, hazy or patchy vision
• new floaters (dots, lines or wispy shapes drifting across your vision)
• finding it harder to see in the dark or in low light
• your vision seeming dimmer, as though you're wearing sunglasses

Symptoms can affect one eye or both. If swelling affects the macula, the part of the retina responsible for your central vision, you may notice changes to what's straight ahead of you while your side vision stays normal. In severe cases, if bleeding fills the eye, your vision can turn completely black.

What are the causes of diabetic eye disease and who is at risk?

Diabetic eye disease happens when high blood sugar levels damage the tiny blood vessels that supply your retina. Over time, these vessels can swell, leak or close off completely, and abnormal new vessels can grow in their place, which is what affects your sight.

Anyone with type 1 or type 2 diabetes can develop eye problems, but your risk is higher if you have:

• had diabetes for many years (the longer you've had it, the higher the risk)
• blood sugar levels that are poorly controlled
• high blood pressure
• high cholesterol
• a high body mass index (BMI)
• kidney disease

Having diabetes also roughly doubles your risk of developing glaucoma, and poor blood sugar control can mean cataracts develop at a younger age. If you're pregnant and have diabetes, retinopathy can also progress faster, though this doesn't apply if you only have gestational diabetes. Children rarely develop sight-threatening retinopathy, though puberty can speed up its progression.

Are there different types of diabetic eye disease?

Diabetic eye disease covers four main conditions: retinopathy, macular oedema, cataracts and glaucoma. Retinopathy itself develops in stages, and your screening results will usually tell you which stage you're at.

• Background retinopathy: small bulges (microaneurysms) appear in the blood vessels at the back of your eye; your sight isn't affected yet
• Pre-proliferative retinopathy: more widespread changes to your blood vessels, with a higher risk your vision could be affected in future; you won't need treatment yet, but you'll be offered screening more often
• Proliferative retinopathy: the most advanced stage, where changes to your blood vessels could affect your sight or cause sight loss; you'll be referred to a specialist for treatment

Diabetic maculopathy is a separate type of retinopathy that affects the macula. In its early stages it causes no symptoms, but in a small number of people it progresses to affect central vision while side vision stays normal.

Macular oedema (swelling of the macula) can develop at any stage of retinopathy and affects around 50% of people who have the condition. Diabetes-related cataracts cause the lens of your eye to become cloudy. Diabetes also doubles the risk of a type of glaucoma that damages the optic nerve.

How is diabetic eye disease diagnosed?

Diabetic eye disease is usually picked up at a diabetic eye screening appointment, where photographs are taken of the back of your eye to check for changes before you'd notice symptoms yourself. If you have diabetes and are 12 or over, you'll be invited for this screening every 1–2 years.

You'll still need separate sight tests at an opticians, as these can pick up other eye problems linked to diabetes, such as glaucoma. If you have diabetes, these NHS sight tests are free.

If screening finds signs of retinopathy or maculopathy, a specialist may use further tests, such as:

• optical coherence tomography (OCT), a scan that checks for swelling at the macula
• fluorescein angiography, a test using a dye to show up the blood vessels in your eye more clearly

Because eye problems can develop early, it's recommended you get screened within three years of a type 1 diabetes diagnosis, straight away after a type 2 diagnosis, and during every trimester if you're pregnant and have diabetes.

How is diabetic eye disease treated?

Diabetic eye disease can't be cured, but treatment can slow it down or stop your sight getting worse. Managing your diabetes well, including your blood sugar, blood pressure and cholesterol levels, protects your eyes at every stage.

Non-surgical treatments

For more advanced retinopathy or macular oedema, your specialist may offer:

• Laser treatment: a laser treats the blood vessels at the back of your eye. A session takes around 30 minutes and you may need more than one. It's done as an outpatient, but your vision will be blurred for a few hours afterwards, so you'll need someone to take you home
• Anti-VEGF injections: a medicine injected into your eye to block a signal, called VEGF, that causes abnormal blood vessels to grow and leak. You'll usually start with injections roughly once a month, tapering off to less frequent visits as your eyes settle
• Steroid implants: used if anti-VEGF injections aren't suitable or haven't worked. A small implant is injected into your eye and releases a steroid medicine over several months to reduce swelling. It dissolves by itself, so doesn't need removing

Surgical treatments

If you have very advanced proliferative retinopathy, for example with heavy bleeding or scar tissue pulling on your retina, you may need vitreoretinal surgery (a vitrectomy). This removes the cloudy gel from the middle of your eye and replaces it with a salt-water solution and can also involve removing scar tissue or reattaching the retina.

The operation is carried out under local or general anaesthetic, through a tiny cut in the white of the eye. You may go home the same day or stay in hospital overnight, and you'll usually need to wear an eye patch for a few days or weeks afterwards while your eye heals.

Cataracts and glaucoma linked to diabetes are treated in the same way as anyone else. Cataract surgery replaces the cloudy lens with an artificial one. Glaucoma is usually managed with eye drops or laser treatment, with surgery available if needed.

When should I see a doctor?

Contact your GP, diabetes care team or an opticians if you have diabetes and notice:

• your eyesight gradually getting worse
• new floaters appearing in your vision
• finding it hard to see in low light

These symptoms don't always mean you have diabetic eye disease, but it's worth getting them checked. Don't wait until your next screening appointment if you notice any changes.

Ask for an urgent GP appointment, or call 111, if you have diabetes and:

• your vision suddenly gets much worse
• you develop sudden blurred vision