Diabetic retinopathy

Diabetes is a condition that causes your blood sugar to be consistently high. This can damage your blood vessels, including those that supply the light-sensitive tissue at the back of your eyes (retina), which is essential for your eyesight. The damaged blood vessels can become swollen, leak fluid or bleed, all of which damage your retina — this is diabetic retinopathy and usually affects both eyes. 

If left untreated, diabetic retinopathy can eventually lead to blindness — around 1,600 people every year in the UK lose their eyesight due to diabetic retinopathy. However, this condition usually develops gradually over time and can be managed to avoid blindness by having regular eye tests to spot problems early and learning to control your blood sugar levels.

Too much sugar in your blood over time can block the tiny blood vessels that supply your retina. In an attempt to restore blood flow, your eye grows new blood vessels but they don’t develop properly and can swell, leak and bleed, damaging your retina.

As diabetic retinopathy worsens, more of the blood vessels supplying your retina become blocked, causing more scar tissue and new blood vessels to form. Together, this can cause your retina to detach or tear. Diabetic retinopathy also increases your risk of other eye conditions, including glaucoma and cataracts.

Diabetic retinopathy affects an estimated 1.5 million people in the UK. Both type 1 and type 2 diabetes can cause diabetic retinopathy. You’re more likely to get diabetic retinopathy if:

• You also have high blood pressure or high cholesterol
• You smoke
• Your blood sugar levels are persistently high ie your diabetes is poorly controlled
• You’re of Asian, African or Afro-Caribbean heritage
• You’re pregnant
• You’ve had diabetes for many years

You probably won’t be able to tell in the early stages of the condition, which is why it’s important to go for regular diabetic eye screenings. Early detection and treatment can help stop it getting worse.

See your GP or diabetes care team immediately if:

• Colours don’t look right
• The quality of your eyesight seems to vary — you may find your central vision is getting worse ie your ability to see things clearly straight ahead of you (eg when reading or driving) 
• You think your eyesight is getting worse or you've had a sudden loss of vision
• Your eyes are red or painful
• Your vision is blurry
• You’re seeing spots or strings (floaters) or dark patches in your vision

These symptoms don’t necessarily mean you have diabetic retinopathy but you need to have your eyes checked for this and other sight-threatening conditions. 

Everyone with diabetes who is aged 12 or older should be screened each year for diabetic retinopathy. 

During retinal screening, you’ll be given eye drops to enlarge your pupils, then photographs of your retina will be taken and sent away for analysis and diagnosis. Your doctor will look for changes in the blood vessels supplying your retina, including new blood vessels. 

If you’re diagnosed with diabetic retinopathy, it will be graded according to how far it’s progressed.

Stages of diabetic retinopathy

There are four stages of diabetic retinopathy:

Mild nonproliferative retinopathy

There are changes in the tiny blood vessels that supply your retina, specifically small bulges in these vessels called microaneurysms. Fluid can leak out of these microaneurysms.

Moderate nonproliferative retinopathy

Blood vessels that supply your retina become swollen and change shape, reducing their ability to effectively deliver blood to your retina. This can cause changes in the appearance of your retina.

Severe nonproliferative retinopathy

Many of the blood vessels that supply your retina are blocked and can't supply blood to your retina. Parts of your retina that don't receive a healthy blood supply start to grow new blood vessels.

Proliferative diabetic retinopathy (PDR)

New blood vessels, which developed in response to the lack of a healthy blood supply to your retina, don't grow properly, passing into the retina and then into the jelly-like substance (vitreous body) that fills your eyeballs. These new blood vessels are more likely to leak fluid and bleed, causing scar tissue to form. Together, this can cause the retina to tear or detach from the underlying tissue — retinal detachment can cause permanent blindness.

Treatment will depend on the stage and grading of your condition.

Management

Controlling your diabetes can prevent or delay your condition getting worse, especially in the early stages. You should:

• Aim to keep your blood sugar, blood pressure and cholesterol at target levels set by your doctor
• Maintain a healthy weight
• Quit smoking
• Take your medication as advised by your doctor

Treatment

If your diabetic retinopathy is more advanced you may be offered:

• A slow-release corticosteroid implant, using an injection, to reduce swelling and inflammation
• Anti-VEGF eye injections to prevent new blood vessels forming
• Eye surgery to remove blood or scar tissue from the eye — scar tissue can be removed via focal or grid macular laser surgery
• Scatter laser surgery to stop or slow the growth of new blood vessels
• Vitrectomy surgery to remove blood that isn't clearing, treat a retinal detachment or stop the growth of new blood vessels if scatter laser surgery wasn't effective enough

• If you smoke, quit
• If you're pregnant and have diabetes have an additional eye examination during your first trimester
• If you're pregnant, tell your optician if you develop gestational diabetes and have an eye examination
• See your optician for an eye examination at least once a year