Diabetic retinopathy

Page last reviewed: 13/07/2011

Diabetic retinopathy is a complication of diabetes in which the retina, a part of the eye, becomes progressively damaged.

During the initial stages, diabetic retinopathy does not cause any symptoms. However, if it is not treated it can cause partial, followed by total, loss of vision.

The National Cancer Screening Service was requested to plan and develop a national diabetic retinopathy screening programme.

The national programme will be a population-based, call-recall programme of screening for sight-threatening diabetic retinopathy. Screening will be by digital photography and will be offered to people with diagnosed diabetes, aged 12 years and over, registered with the programme. The programme will be delivered locally and provided to the highest, internationally comparable, quality assured standards.

What is diabetes?

Diabetes is a condition in which the body does not produce enough insulin or cannot use insulin properly. Insulin is a hormone that helps break down glucose (sugar) so that it can be used by the body's cells as fuel.

The body's problem with making or using insulin causes the level of glucose in the blood to rise. This can cause a wide range of complications, including diabetic retinopathy.

There are two types of diabetes, which are described below.

Type 1 diabetes

In type 1 diabetes, the body does not produce any insulin. The condition usually begins in people who are under 40 years of age and often develops during the teenage years. People with type 1 diabetes will need injections of insulin for the rest of their life.

Type 2 diabetes

Type 2 diabetes is where the body does not produce enough insulin to function properly or where the body's cells do not react to insulin.

Being overweight or obese is a major risk factor for type 2 diabetes. Type 2 diabetes can develop at any age, but usually affects people who are 45 years of age or over. Some people with type 2 diabetes can control their symptoms using a combination of diet and exercise. More serious cases require insulin injections.

Type 2 diabetes is the most common type of diabetes, accounting for around 90% of all cases.

How common is diabetic retinopathy?

Diabetic retinopathy is a common complication of diabetes. It is the leading cause of blindness in adults under the age of 65.

It is estimated that 25% of people with type 1 diabetes will have some degree of diabetic retinopathy five years after their symptoms first develop.

In the case of type 2 diabetes, 25% of people who do not require insulin will have some degree of diabetic retinopathy five years after the onset of symptoms. The figure is higher for people who require insulin (an estimated 40%).

Outlook

If diabetic retinopathy is diagnosed and treated at an early stage, the outlook for the condition is good. Research has found that treatment can prevent severe vision loss in 90% of cases of diabetic retinopathy.

Early stage diabetic retinopathy can usually be treated by bringing your diabetes under better control. More advanced diabetic retinopathy will require laser surgery to prevent further damage to the eyes.If you have a condition which may interfere with your ability to drive you should inform your doctor and the Road Safety Authority(RSA).

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Page last reviewed: 13/07/2011

Diabetic retinopathy does not usually cause any symptoms until it has reached an advanced stage. In some cases, the only noticeable symptom is a sudden and complete loss of vision. This is why regular screening is so important.

Symptoms of diabetic retinopathy include:

  • discoloured spots (known as floaters that 'float' in your field of vision 
  • blurred vision
  • your vision becomes blocked by patches or streaks
  • reduced night vision, and, most seriously
  • sudden vision loss

When to seek medical advice

People with diabetes are 20 times more likely to experience vision problems than the rest of the population. Therefore, it is very important that you take any potential problems with your eyes seriously.

If you experience any of the symptoms above or have any other problems with your eyesight, contact your diabetes care team or your GP as soon as possible.

GlossaryBlood
Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.
Blood vessels
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.
Retina
The retina is the nerve tissue lining the back of the eye, which senses light and colour and sends it to the brain as electrical impulses.
Tissue
Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.

Page last reviewed: 13/07/2011

To understand the causes of diabetic retinopathy, it useful to know how your eyes and, in particular, your retina work.

The retina and the eye

The eye works in a similar way to a camera. At the front of your eye is a series of lenses. These help focus and then transmit light signals coming into the eye.

The light signals are sent to the retina, which is similar to the film that is used in a traditional camera. The retina consists of a layer of light-sensitive tissue that can capture and store an image produced by the incoming light. The retina then relays the image to the brain through the optic nerve (the main nerve that connects each eye to the brain).

At the centre of the retina is a small area of highly specialised and sensitive tissue. This is known as the macula. The macula is the most important part of the retina because it is used for activities that require a high degree of focusing, such as reading and writing. It is also used to distinguish one colour from another.

Diabetes can damage the retina

As with all parts of the body, the retina requires a constant supply of blood to survive. The blood is supplied by a network of tiny blood vessels.

It is thought that, over the course of many years, the high glucose levels associated with diabetes can damage the blood vessels that supply the retina with blood.

In the initial stages of diabetic retinopathy, the damage is limited to tiny bulges (microaneurysms) that develop in the walls of the blood vessels. Occasionally, microaneurysms can leak blood and fluid, although this does not usually affect your vision.

Over time, damage can develop in the blood vessels that supply the macula. This can lead to some vision loss, which can affect both seeing things clearly at a distance and seeing things in fine detail, such as the small print in a document.

As diabetic retinopathy reaches its most advanced stage, some of the blood vessels that supply your retina will become blocked. To compensate for this, your body will start to produce new blood vessels to restore the supply of blood.

As the new blood vessels are unstable and prone to bleeding, they can cause blurred and patchy vision as the blood obscures your sight. Over time, the bleeding can lead to the formation of scar tissue. There is a risk that this will pull your retina out of position. This is known as retinal detachment.

Retinal detachment can lead to a darkening of vision, floaters and, if left untreated, a total loss of vision.

Risk factors

There are a number of risk factors that increase your chances of developing diabetic retinopathy.

Duration of diabetes

The biggest risk factor for diabetic retinopathy is the length of time that you have lived with diabetes.

For people with type 1 diabetes, 90% will have some degree of diabetic retinopathy after 10 years of having symptoms.

For people with type 2 diabetes who do not need to take insulin, 67% will have some degree of diabetic retinopathy after 10 years of symptoms.

For people with type 2 diabetes who need to take insulin, 79% will have some degree of diabetic retinopathy after 10 years of symptoms.

Blood glucose level

The higher the levels of glucose in your blood, the greater your risk of developing diabetic retinopathy. People with high blood glucose levels are more likely to progress to advanced diabetic retinopathy.

Blood glucose levels are measured using a test known as the HbA1c test. HbA1c is a form of haemoglobin, the oxygen-carrying chemical in red blood cells that has glucose attached to it.

Small changes in the levels of HbA1c can greatly affect the risk of developing diabetic retinopathy. For example, people with an HbA1c level of 8% are 40% more likely to develop diabetic retinopathy than people with an HbA1c level of 7%.

High blood pressure

People with high blood pressure (hypertension) are likely to progress to advanced diabetic retinopathy.

Risk factors for high blood pressure include:

  • age (the risk of developing high blood pressure increases as you get older)
  • family history of high blood pressure (the condition seems to run in families)
  • being of African-Caribbean or south Asian origin
  • obesity
  • lack of exercise
  • smoking
  • excessive alcohol consumption
  • a high amount of salt in your diet
  • a high-fat diet
  • stress

While not all of these risk factors (such as age and ethnicity) are avoidable, most of them are. Therefore, taking steps to prevent getting high blood pressure will also help reduce the risk of diabetic retinopathy.

See Prevention of high blood pressure for more information.

GlossaryBlood vessels
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.
Kidneys
Kidneys are a pair of bean-shaped organs located at the back of the abdomen, which remove waste and extra fluid from the blood and pass them out of the body as urine.
Tissue

Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.

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Page last reviewed: 13/07/2011

Stages of diabetic retinopathy

If diabetic retinopathy is detected during screening, you will be given information about how far the condition has progressed. This will determine the type of treatment you will receive.

The stages of diabetic retinopathy are described below.

Background retinopathy

Background retinopathy is the first stage of diabetic retinopathy. There is evidence of microaneurysms (tiny bulges in blood vessels) and some mild bleeding.

Pre-proliferative retinopathy

Pre-proliferative retinopathy is the second stage. By this stage there are signs that the blood supply to the retina is reduced and there are multiple points of bleeding.

Proliferative retinopathy

Proliferative retinopathy is the third stage. New blood vessels have formed in the retina. These may bleed resulting in the development of scar tissue and there may be some degree of retinal detachment.

Maculopathy

The Macula is the area of the retina responsible for central vision and seeing fine detail. Maculopathy is where there leakage of fluid from blood vessels at the macula resulting in loss of central vision.

Glossary

Blood
Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.
Blood vessels
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.
Retina

The retina is the nerve tissue lining the back of the eye. It senses light and colour and sends it to the brain as electrical impulses.

 

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Meet the ophthalmic team

  • An optometrist examines eyes, tests eyesight and prescribes and provides spectacles and contact lenses. Optometrists are trained to recognise defects in eyesight and eye diseases, and some prescribe treatment for common eye conditions.
  • An ophthalmologist is a medical doctor who specialises in eye disease and its treatment or surgery. They mainly work in hospitals and hospital eye departments.
  • A dispensing optician fits prescriptions for spectacles provided by optometrists, OMPs or ophthalmologists. They may also fit contact lenses after undergoing specialist training. A dispensing optician doesn't examine the eyes.
  • An orthoptist specialises in problems relating to the development of vision in children. They help to identify and treat squints, lazy eyes and double vision.
  • An ophthalmic nurse is a nurse who has skills in eyecare. Ophthalmic nurses work in hospital eye departments.

Page last reviewed: 13/07/2011

Your treatment plan

Treatment for diabetic retinopathy will vary depending on what stage the condition has reached.

Background retinopathy

Background retinopathy requires no immediate treatment, but you should have annual eye examinations by an ophthalmologist (eye specialist) so that the condition's progress can be carefully assessed.

Pre-proliferative retinopathy

If pre-proliferative retinopathy is detected during screening, you will be referred to an ophthalmologist for a more detailed assessment of your condition.

If the amount of bleeding is minimal, no immediate treatment is required. However, you will need regular eye examinations (once or twice a year, depending of the severity of your symptoms) so that the condition can be monitored. You may also be given additional treatment to bring your diabetes under better control. See Treating diabetes for how to control your diabetes more effectively.

Laser treatment may be recommended if the amount of bleeding is excessive.

Maculopathy and proliferative retinopathy

Laser treatment is usually recommended for both maculopathy and proliferative retinopathy to prevent further loss of vision.

In advanced proliferative retinopathy, laser treatment may not be possible and a type of eye surgery called vitreous surgery may be required.

Laser treatment

The type of laser treatment used to treat diabetic retinopathy is known as photocoagulation. Photocoagulation involves using a laser to burn away any abnormal blood vessels.

A course of photocoagulation involves one or more visits to a laser treatment clinic. Treatment is normally available on an out-patient basis. It is not usually painful, but you may feel an occasional sharp pricking sensation when certain areas of your retina are being treated.

Drops are put into your eyes to numb the surface. A special contact lens is then placed on your eye to hold your lids open and to focus the laser beam on your retina.

If you have had a number of laser sessions in the past, you may feel some discomfort during the treatment. If you have felt discomfort in the past, ask the doctor to give you painkillers or a mild sedative.

Your vision will be blurred after treatment, but this should return to normal after a few hours. If you have a lot of treatment on your eyes, it can cause them to ache. Over-the-counter (OTC) painkillers, such as paracetamol, should help ease the pain.

Sometimes, photocoagulation can damage the outer retina. If this occurs, there is a chance that your night and peripheral vision (your ability to see to objects that are outside your direct gaze) may be affected.

More than 50% of people who have laser treatment for diabetic retinopathy notice some difficulty with their night vision, and 3% notice some loss of peripheral vision.

Seek medical advice if you experience any new eye problems following treatment.

Intravitreal Injections

Intravitreal injections are injections into the vitreous gel inside the eye. They are used alone or in combination with laser treatment to treat maculopathy. Most patients will require at least 3-4 injections initially at intervals of 4-6 weeks and may require further injections depending on the response to treatment.

Vitreous surgery

Vitreous surgery is often required if:

  • a large amount of blood has collected in the centre of the eye, obscuring your vision, or
  • there is extensive scar tissue which is likely to cause, or has already caused, retinal detachment

The surgeon will make a small incision in your eye before removing the vitreous gel that sits in front of the retina. The vitreous gel is where the blood gathers.

Any scar tissue will be removed from your retina and, in some cases, the retina may be strengthened in position using tiny clamps. The vitreous gel will be replaced with a gas or liquid to help hold the retina in place. The gas or liquid will gradually be absorbed by your body, which will create new gel to replace the gel that was removed during surgery.

Vitreous surgery is usually performed under local anaesthetic and sedation. This means that you will feel no pain and have little or no awareness of the surgery being performed.

You should be able to go home on the same day or the day after your surgery.

For the first few days after surgery, you may be asked to wear an eye patch so that you can gradually make more and more use of your eye. This is because activities such as reading and watching television can quickly tire your eye.

If gas was used to hold your retina in place, you should not travel by air until all of the gas has been absorbed by your body. Your surgeon will be able to advise you about this.

Following vitreous surgery, it is normal to have blurred vision for several weeks. This should begin to improve gradually, though it may take several months before your vision returns to normal.

GlossaryBlood
Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.
Blood vessels
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.
Retina

The retina is the nerve tissue lining the back of the eye. It senses light and colour and sends it to the brain as electrical impulses.

Useful Links

Page last reviewed: 13/07/2011

Blood sugar levels

To prevent or slow the progression of diabetic retinopathy, it is very important to keep your blood sugar level as close to normal as possible.

In home testing, blood glucose levels are usually measured in millimoles of glucose per litre of blood, or mmol/l. A millimole is a measurement that is used to define the concentration of glucose in your blood.

Blood glucose levels vary from person to person and the amount of glucose in your blood will change throughout the day. Therefore, there is no such thing as an 'ideal' blood glucose level.

However, a normal blood glucose level is 4-6 mmol/l before meals (preprandial) and less than 10 mmol/l two hours after meals (postprandial). Your diabetes care team can discuss your blood glucose level with you in more detail.

Find out how to test your glucose levels.

High blood pressure

Having high blood pressure (hypertension) can make the blood vessels in your eyes more vulnerable to damage, increasing your risk of developing advanced diabetic retinopathy.

The most effective way of preventing high blood pressure is to eat a healthy, balanced diet, including plenty of fruit and vegetables (at least five portions a day), and to take regular exercise (at least 30 minutes five times a week).

If you smoke, you should try to quit because smoking can increase your blood pressure, see www.QUIT.ie.

The recommended limits for alcohol consumption are 17 standard drinks a week for men and 11 for women. A standard drink of alcohol is equal to about half a pint of beer, a small glass of wine or a pub measure of spirits

Screening

It is very important that you attend your annual diabetic retinopathy screening appointment. The earlier any problems with your eyes are detected, the greater the chances of successful treatment.

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Page last reviewed: 13/07/2011

When blood vessels grow within your retina, they sometimes burst, or leak fluid. This can interfere with the normal blood flow to your eye, and may lead to complications. The main complications of diabetic retinopathy are:

  • Bleeding in the eye (vitreous haemorrhage) - if the bleeding from new blood vessels is small, you may only have temporary spots inferring with your vision. However, in more serious cases, blood may completely fill your eye blocking your vision completely. This bleeding does not cause permanent vision loss, and often clears up after a few week or months.
  • Traction retinal detachment - is where part of your eye is pulled out of its normal position. This happens as a result of scar tissue that forms at the back of your eye after the new blood vessels have grown. When the scar tissue shrinks, it pulls the retina away from the wall of your eye causing blank or blurred vision. In severe cases, this can cause complete loss of vision.
  • Neovascular glaucoma - alongside the leaking of blood vessels and abnormal growth of new vessels in your retina, you may also experience abnormal blood vessel growth within your iris (the coloured part of the eye that controls the amount of light that enters). This can disrupt the normal flow of fluids in your eye causing pressure to build up, potentially leading to damage to your optic nerves and, in severe cases, can cause permanent damage to your vision.

     

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Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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