Diabetic macular oedema (DMO) is the most common cause of sight loss in diabetics. Oedema means fluid retention. When leaky vessels cause fluid to build up in the macula, at the centre area of the retina, it is known as diabetic macular oedema. It is a complication of diabetic retinopathy and results in a condition very similar to wet AMD.
People with diabetes are at particular risk of damage to their eyesight. The longer you have diabetes, the greater your chance of developing sight loss.
To work properly, the eye needs a constant supply of blood. When control of blood sugar levels is poor, the blood vessels of the eye become damaged and leak, which is known as diabetic retinopathy. About 90 per cent of people with type 1 diabetes will have some degree of retinopathy after 10 years. For people with type 2 diabetes, the chance of developing retinopathy after 10 years is between 67 and 80 per cent.
Small changes in your blood sugar levels can significantly affect your risk of developing retinopathy, and the risk is higher if you also have high blood pressure. Overall, seven per cent of people with diabetes will have noticeable loss of vision through DMO.
In the early stages of diabetes you may not notice any effect on your vision. If damage causes only small bulges in the blood vessels of the retina, your eyesight can remain good. However, when the blood vessels in or near the macula become damaged, or there is a sudden bleed or leak into the macula, your sight can worsen dramatically.
Look out for dark spots, like a smudge on glasses, or gaps appearing in your vision, especially first thing in the morning. Objects might appear to change shape, size or colour, or disappear. Colours can fade and you may find bright light or glare difficult. You may experience difficulty reading, and straight lines such as door frames and lampposts may appear distorted or bent.
If you notice a sudden change in your vision, contact your optometrist or hospital eye specialist urgently.
DMO can be treated if it is caught early. Although treatments cannot restore sight if there is already significant damage to the macula, they can slow the rate of damage and preserve more of your sight for longer.
Anti-VEGF drugs are injected into the eye to stop fluid leaking from the blood vessels. You will usually have a number of injections in the first few months, then more if later check-ups suggest they are needed.
Some people, including those who have had cataract surgery, may be offered a steroid injection instead. A tiny implant is injected into the eye to gradually release the steroid over several months.
If your DMO doesn’t involve the centre of the macula, you may be offered laser treatment. This usually requires one or more visits to an outpatient laser clinic for treatment by an ophthalmologist.
Diabetes is a lifelong condition, so maintaining a healthy lifestyle and monitoring your blood sugar, blood pressure and cholesterol levels is crucial to avoid damage to your eyes.
New drugs are being developed to prevent blood vessels leaking even more effectively, and which could be taken as eye drops rather than injections. Other existing drugs are also being tested as possible treatments for DMO, including tablets that are usually used to treat people with high cholesterol.