Diabetic macular oedema (DMO)
Diabetic macular oedema is a complication of diabetes. It happens when blood vessels in the retina at the back of the eye leak, causing fluid build-up at the macula. The leakage occurs when high blood sugar levels damage blood vessels.
The macula provides the central vision for seeing fine details, reading, watching television and many other daily activities. That's why diabetic macular oedema (DMO) can lead to loss of vision and is the leading reason for vision loss among people with diabetes (Source: Ophthalmology).
If you have either type 1 diabetes or type 2 diabetes, it's important to follow the advice of your healthcare team about managing your blood sugar levels to help reduce the risk of diabetic eye disease. You should also have an annual diabetic eye screening appointment to monitor for changes to your eyes. Early detection and treatment can help limit vision loss.
A diagram of a healthy eye with labels.
A diagram of an eye with diabetic macular oedema. The diagram shows the retina swollen with fluid from damaged blood vessels.
What are the symptoms of diabetic macular oedema?
Diabetic macular oedema is painless and can develop over many years. You might not notice any symptoms at first, making it all the more important to go for regular diabetic eye screening.
Diabetic macular oedema can cause changes to your sight, so be aware of symptoms which can include:
- A dark or black spot in your field of vision
- Developing blurry or distorted vision
- Blue-yellow colour blindness
- Colours appearing faded or washed out
- Loss of contrast sensitivity
- Trouble with glare from bright lights
- Straight lines appearing wavy or bumpy
Diabetic macular oedema can ultimately lead to permanent damage and scarring at the macula, which cannot be reversed. It affects the central vision we use for seeing fine details, colours and looking straight ahead for activities like reading, watching television, driving, and recognising faces. The vision loss it causes can be stabilised with early treatment, and it doesn't affect your side vision.
Diabetic macular oedema treatment
Early treatment can be effective at preventing further vision loss with diabetic macular oedema. That's why regular diabetic eye screening is important to detect the condition as early as possible.
Treatment options can include a series of eye injections and sometimes laser treatment. The best treatment depends on your personal circumstances and diagnosis. Your doctor will discuss the treatments, likely results, and possible side effects with you.
What causes diabetic macular oedema?
Diabetic macular oedema can affect all people with diabetes, whether they have type 1 diabetes or type 2 diabetes. Around one in 14 people with diabetes develop diabetic macular oedema (Source: Ophthalmology).
The condition happens when high blood sugar levels damage the blood vessels in the light-sensitive retina at the back of the eye. Diabetic macular oedema happens when these damaged blood vessels leak into the macula at the centre of the retina. This fluid stops the retina from working properly, and when this affects the macula it can affect the central vision.
Risk factors when you have diabetes include high blood sugar levels, high cholesterol, and high blood pressure. These can increase your risk of developing diabetic retinopathy, which can lead to diabetic macular oedema.
Diabetic macular oedema diagnosis
Regular diabetic eye screening can detect diabetic macular oedema, often before noticeable symptoms develop. If you might have diabetic macular oedema, you will be referred to hospital for further tests, which can include:
- A dilated eye test: you'll be given eye drops that dilate your pupils, so an eye specialist can examine the back of the eye in detail.
- An optical coherence tomography scan (OCT): this special camera uses light waves to create a detailed image of the retina. It's not an invasive test; you just look into the machine for a few seconds.
- Fluorescein angiography: you have a dye injected into your arm, which shows up in the blood vessels in the retina. This allows a detailed look at the back of the eye.
These tests help determine what type of diabetic macular oedema you have. When the very centre of the macula, known as the fovea, is involved, this is known as 'centre-involving DMO'. If the fovea isn't affected, it's known as non-centre involving DMO. Another type of diabetic macular oedema happens when the blood vessels supplying the macula shut down completely, which leads to sight loss.
When to get medical advice
Everyone aged 12 and older with diabetes should have a diabetic eye examination at least once a year. These eye exams monitor your eyes for early signs of diabetic eye disease before you experience vision problems.
Living with diabetic macular oedema
It's normal to worry if you're diagnosed with a condition like diabetic macular oedema. You'll be dealing with treatment, managing your diabetes, and having check-ups to monitor any changes to your sight.
What's more, you might worry about how you'll cope if you do experience some loss of vision. Talking to friends and family about your feelings can help, as can talking to people with experience of living with diabetic macular oedema. There's also lots of practical support to help you adjust and make the most of your vision.
Frequently asked questions
Medically reviewed by: The Royal College of Ophthalmologists on 18/10/2022
Edited by: Nick Astbury FRCS FRCOphth FRCP
Clinical Associate Professor
LSHTM
The Royal College of Ophthalmologists champions excellence in the practice of ophthalmology and is the only professional membership body for medically qualified ophthalmologists. The RCOphth is unable to offer direct advice to patients. If you’re concerned about the health of your eyes, you should seek medical advice from your GP, optometrist or ophthalmologist.