Diabetic retinopathy is an eye condition related to diabetes, and it happens when the blood vessels in the eye are damaged by high blood glucose levels. If the condition isn’t diagnosed and treated it can lead to blindness, however this stage can take several years to reach.
Signs & Symptoms
As diabetic retinopathy doesn’t present noticeable symptoms until the condition develops over time, early signs are usually picked up during a diabetic eye screening – this is when photographs of your eyes are taken to check for damage. However you should alert your GP or diabetic carer if you experience any of the following:
- Your vision becomes steadily worse.
- You suddenly lose your vision.
- You start seeing floaters (shapes floating in your eyes).
- Your vision becomes blurred.
- You feel pain in your eyes.
- Your eyes become reddened.
These symptoms may not always indicate diabetic retinopathy, but as diabetics may be at extra risk of eye damage it’s important to get any symptoms looked at.
Complications of Diabetic Retinopathy
Diabetic retinopathy can lead to other complications within the eye:
Retinal Detachment – Proliferative diabetic retinopathy is a later stage of the condition where fragile new blood vessels are formed in the eyes. These can bleed easily, and scar tissue that accompanies it can cause the retina to become detached.
Diabetic Maculopathy – The central area of the retina is known as the macula, and it’s responsible for the type of vision we use to read or drive. Diabetic maculopathy is when the macula is damaged – an example of macular damage is a diabetic macular oedema, which involves fluid leaking into the macular and causing loss of vision.
Rubeosis Iridis – This is when blood vessels grow in the coloured part of the eye called the iris. It may cause a reddish colour to develop in the iris, but it can also lead to neovascular glaucoma, a severe form of glaucoma that can be very painful.
What Causes Diabetic Retinopathy?
Diabetic retinopathy occurs as a complication of diabetes; as high levels of blood glucose can damage the blood vessels in the eye. The following factors can increase the risk of developing the condition:
- If you have been diabetic for a long period of time.
- If your blood glucose levels are regularly high.
- If your blood pressure or cholesterol are high.
- If you are pregnant.
- If you have an Asian or Afro-Caribbean Background.
How Your Eye Works: The Retina
The retina is a patch of light-sensitive cells at the back of the eye that works by converting light into electrical signals, which are sent to the brain via the optic nerve. A network of blood vessels in the eye provide a constant supply of blood for the retina, however these can become damaged as a result of elevated blood glucose, leading to diabetic retinopathy. This can happen in three stages.
Stages of Diabetic Retinopathy
This is when the blood vessels grow small swellings (microaneurysms) that might bleed a little, but will not normally damage your vision. This stage doesn’t require treatment, however it increases the risk of your vision deteriorating further, making it important to take preventative measures against the condition getting worse.
In this stage more changes occur in the retina, including an increased amount of bleeding. The risk of your vision being affected also rises, therefore you may be asked to attend more eye screenings so eye care specialists can monitor your condition.
Proliferative retinopathy is when your retina develops news blood vessels as well as some scar tissue. Any vision loss at this stage will be permanent, and the risk of losing your vision completely increases, therefore you will be offered treatment such as laser surgery or eye surgery. This stage can also lead to significant bleeding in your eyes, as well as complications such as retinal detachment and diabetic maculopathy.
How is Diabetic Retinopathy Diagnosed?
As diabetic retinopathy may not present symptoms until your vision is already affected, the NHS offers a yearly diabetic eye screening to all diabetics from twelve years old onwards. The screening can detect irregularities in your eyes before your vision becomes affected, which can help you prevent vision loss from happening or stop it from deteriorating further if it has already started.
Diabetic Eye Screening
Your nearest Diabetic Eye Screening Service should send you an invitation to have your eyes examined, but if not you should contact your GP or local screening service. When you have your screening you should bring any lenses you wear, including the lens cleaning solution you use if you wear contacts.
Your normal eye exams won’t cover what happens in a diabetic eye screening and the screenings themselves won’t detect any other eye conditions, therefore it’s still important to see your optician frequently.
What Happens In a Diabetic Eye Screening?
The process will be outlined by the specialist who carries out the exam, who should also answer any questions you have.
The specialist will administer eye drops that work by expanding your pupils, this can take fifteen to twenty minutes. You may experience a stinging feeling, blurred vision, or difficulty focusing on near objects.
These effects can last for up to 6 hours, therefore you might want to bring someone along who can drive you back home after the appointment.
The healthcare professional will then take photographs of your retina. The camera won’t touch your eye, and it may give a bright flash but this should not cause much discomfort. It may also help to bring sunglasses as the procedure can leave everything looking quite bright afterwards.
The eye drops used in diabetic eye screenings can cause a sudden increase in intra-ocular pressure, although this is rare. If this happens you may experience pain or discomfort in your eyes, reddening of your eyes, blurred vision or halos around lights. If you display any of these symptoms, you should go back to the screening centre or the closest A&E department as it will require fast treatment.
The results normally take up to six weeks to arrive as a number of eye care professionals will analyse the photographs. When you get the results they will indicate that:
- You have no retinopathy.
- You have background or stage one retinopathy.
- You have a degree of referable retinopathy that requires additional assessment and treatment by an eye specialist.
Further investigation may also be required if the photographs are not clear enough, if they detect signs of another eye condition such as cataracts or glaucoma, or if your retinopathy requires more attention or treatment.
Other Exams and Tests
There are a variety of other exams you may be given if you are a diabetic:
- A visual acuity test examines your ability to focus at close and far distances and can help identify a loss of vision.
- An ophthalmoscopy and slit lamp exam show the doctor the structure of your eye, letting them detect cataract formation, retinal alterations, and other eye conditions.
- A gonioscopy looks at the drainage angle of your eyes. This can help detect glaucoma, which could happen as a result of severe retinopathy.
- A tonometry measures intraocular pressure, which is also used to detect glaucoma.
- An optical coherence tomography checks for retinal fluid that can indicate diabetic maculopathy.
- A fluorescein angiogram detects and examines any blood vessels that are leaking in the retina.
- Fundus photography is used to track progress in people who have diabetic retinopathy.
How do you treat Diabetic Retinopathy?
Treatment is normally only offered if the retinopathy has reached the proliferative stage or if you present symptoms of diabetic maculopathy. If this is the case, the main options are laser treatment, eye injections, and eye surgery.
Laser treatment for diabetic retinopathy involves treating the blood vessels that have formed in your eyes as a result of the retinopathy progressing. The lasers stabilise the weak blood vessels to prevent them from bleeding into the eye, because otherwise bleeding can lead to diabetic maculopathy.
During the laser surgery, local anaesthetic is used to numb your eyes and you are given eye drops to enlarge your pupils. Your eyelids are then held open by contact lenses that allow the laser to focus on your retina.
You shouldn’t feel any pain as the procedure takes place, however there may be a slight pricking sensation. The process usually takes between 20 and 40 minutes and you won’t need to stay overnight, however you may be required to visit the laser treatment clinic again.
Laser surgery may have side effects that can last for a few hours, such as:
- Photophobia – Your eyes may be more sensitive to light, therefore you might want to wear sunglasses after the surgery.
- Discomfort – You may also experience some aching that can be helped by painkillers you buy over the counter.
- Blurry Vision – The laser surgery can leave your vision blurred. This means you will be unable to drive; therefore, you should organise another way to get home.
There are risks associated with all medical procedures including laser surgery, and you should be informed of these before undergoing the procedure.
- You may see floating shapes in your vision.
- Your night vision or peripheral vision may weaken.
- You might ‘see’ the imprint of the laser on the back of your eye.
- You could experience bleeding in the eye.
- There may be a small blind spot in the centre of your field of vision.
If you notice any of these symptoms or if your vision decreases after surgery you should seek medical attention.
If you develop diabetic maculopathy as a result of the retinopathy progressing, you may be given anti-VEGF injections. These are injected directly into your eyes to stop the formation of new blood vessels. The anti-VEGF injections are normally administered once a month, becoming less frequent as your vision stabilises. The treatment procedure involves:
- Cleaning and covering the skin around your eyes.
- Using small clips to hold your eyes open.
- Numbing your eyes with local anaesthetic.
- Guiding a fine needle into your eyeball to administer the injection.
In some cases steroids may be injected either in place of the anti-VEGF injections or if the injections do not work.
Anti-VEGF injections may have the following side effects:
- Your eyes may become irritated or uncomfortable.
- Your eyes might begin bleeding.
- You may start seeing floaters.
- You might feel like there is something in your eye.
- Your eyes may become itchy and dry.
- Your eyes might water.
The anti-VEGF injections also carry a small risk of forming blood clots, which can lead to you having a heart attack or stroke, while steroid injections can cause an increase in intraocular pressure.
If there has been significant bleeding in your eye, or there is scar tissue that increases the risk of retinal detachment, you may be offered an operation called vitreoretinal surgery to take away part of the vitreous humour.
A small incision is made in the eye before some of the vitreous humour is removed along with any scar tissue. A laser is then used to prevent your vision from getting worse.
You may need to wear a patch over the affected eye as it can become fatigued quickly due to activities such as reading or watching television. Your sight may also be blurry but this will steadily get better.
Risks and Side Effects
Vitreoretinal surgery can carry the following risks:
- You may develop a cataract.
- You may experience bleeding in your eye.
- Your retina may become detached.
- Fluid may build up in your cornea.
- Your eye may become infected.
You may also be required to undergo further retinal surgery later on.
How Do You Prevent Diabetic Retinopathy?
Making sure your blood sugar, blood pressure, and cholesterol are well controlled can help lower the risk of developing diabetic retinopathy.
You can do this by adopting a healthy lifestyle. To do this you should:
- Eat according to a balanced diet, cutting down on sugar, salt, and fat.
- Try to lose weight if you’re overweight, aiming for a BMI of 18.5 - 24.9.
- Exercise regularly, for roughly two and a half hours a week. This can include walking, running, or cycling.
- Stop smoking if you are a smoker.
- Limit your alcohol intake to less than 14 units a week.
You may be given medication such as insulin or metformin for your blood sugar, ACE inhibitors for your blood pressure, or statins for your cholesterol.
Knowing what numbers you should be aiming for can help you control your blood sugar, blood pressure, and cholesterol.
- Blood Sugar – You should aim for a blood sugar level between 4 and 10 mmol/l. Your GP will also measure your average blood glucose level from the past few weeks – this is known as HbA1c, and should be around 48 mmol/l for people with diabetes. You can buy blood sugar monitors commercially, or your GP or hospital may give you one.
- Blood Pressure – If you have diabetes you should aim for no more than 140/80mmHg or less than 130/80mmHg if your diabetes is causing complications. Blood pressure monitors can be bought to use at home.
- Cholesterol – With diabetes your blood cholesterol should be no more than 4mmol/l. Cholesterol levels are usually determined by a blood test you can have at your GP surgery.
You should always attend your annual diabetic eye screening – as you may not notice the effects of diabetic retinopathy, detecting the symptoms early can prevent you from losing your vision in the future.