Diabetic eye disease

Written by: 
Dr Roger Henderson

Diabetes is one of the most common metabolic disorders in the world. The longer a person has the condition, the greater his or her chance of developing diabetic eye disease.

The most common form of diabetic eye disease is diabetic retinopathy Any disorder of the retina, the innermost layer of the eye.(DR), which is the most frequent cause of blindness in people of working age in the Western world.[1]

Other eye problems linked to diabetes include cataracts, premature glaucomaIncreased pressure within the eye (intraocular pressure), which leads to visual loss., rubeosis iridis, nerveBundle of fibres that carries information in the form of electrical impulses. palsies, asteroid hyalosis and ischaemic optic neuropathy.

If you have diabetes, you will probably be referred to have your eyes checked when you are diagnosed, and thereafter ideally your eyesight should be checked at least once a year for life.[2] In addition, it is important to have your eyes examined urgently if you notice any of the warning signs of diabetic eye disease.

Diabetic retinopathy

High levels of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. in the body over a long period of time cause damage to the very small bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels at the back of the eye. The vessels begin to leak and then become blocked.

This causes spots of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. (called haemorrhages) and proteins (exudates) to develop on the retina at the back of the eye, and this can in turn cause swelling and the formation of abnormal bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels.

For people who may develop diabetic retinopathy the main areas of concern and points of interest are:

What are the risk factors?

If you have diabetes, the better you control your bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. sugar, the less chance there is of changes related to diabetic retinopathy occurring. Other risk factors that can influence the severity and progression of diabetic retinopathy include:

  • High bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressure
  • Obesity
  • High cholesterolA substance present in many tissues and an important constituent of cell membranes although high concentrations of a certain type of cholesterol in the blood are unhealthy. levels in the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid..

Smoking will also worsen the condition.

Can diabetic retinopathy be prevented?

It is always far better to prevent diabetic eye disease than to treat it once it has developed. Because of this, it is important to keep as strict a control of your bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. sugar as possible, and to control other risk factors such as being overweight, having high blood pressure or high levels of fatOne of the three main food constituents (with carbohydrate and protein), and the main form in which energy is stored in the body. in the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid..

It is important to try to prevent the development of diabetic retinopathy. For example, figures from Europe show that 65 in every 100,000 people with diabetes become blind each year as a result of diabetic retinopathy.[3] The formation of abnormal bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels affects around 40 per cent of those with diabetes in Europe after 20 years with diabetic retinopathy, while bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessel leakage affects around 20 per cent over the same time.[4]

What are the classifications of diabetic retinopathy?

There are six main classifications of diabetic retinopathy:

  • No background retinopathy at all
  • Background diabetic retinopathy Any disorder of the retina, the innermost layer of the eye.- signs of microleakage from bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels
  • Maculopathy - worsening bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessel leakage
  • Preproliferative - leakage and signs of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessel blockage developing
  • Proliferative - new bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels start to form on the retina
  • Advanced - bleeding, often with detachment of the retina and other complications.

What are the symptoms of diabetic retinopathy?

One of the problems with diabetic retinopathy is that there are often no symptoms at all in its early stages. Later symptoms include the following:

  • If fluid begins to develop at the back of the eye (known as macular oedemaThe accumulation of excess fluid in the tissues of the body.) then blurred vision develops
  • If new bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels start to form on the surface of the retina they can bleed into the eye, causing spots of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. to 'float' into vision, as well as causing blocked vision
  • If a large bleed occurs (a vitreous haemorrhageThe internal or external loss of blood from a blood vessel.) it can cause sudden loss of vision in that eye.

How is diabetic retinopathy treated?

Treatment varies according to the classification:

  • Background retinopathy Any disorder of the retina, the innermost layer of the eye.- regular eye examinations are essential but no treatment is required
  • Maculopathy - this is treated with laser photocoagulation. This involves using laser treatment on the back of the eye to make a series of small burns that destroys abnormal parts of the retina and seals any leaking areas. It is carried out in hospital using local anaestheticA medication that reduces sensation in a part of the body. eye drops so is a painless procedure. The number of burns applied varies between individual patients
  • Proliferative retinopathy Any disorder of the retina, the innermost layer of the eye.- pan-retinal photocoagulation A technique using heat from a light source for destroying diseased tissue in the retina, the innermost layer of the eye. retinopathy (PRP) is used.[5] Laser burns are scattered over the whole of the retina in order to destroy areas starved of oxygen and so reduce or prevent new bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels forming there. Up to 1,500 burns can be made over 2 to 3 sessions
  • Surgery is only rarely required, but may be needed if laser treatment does not work, if proliferative retinopathy has been identified at a very late stage or if there has been serious bleeding into the eye. The procedure, known as a vitrectomy, involves removing the vitreous jelly-like substance from the back of the eye along with any bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. clots. Laser treatment may also be used at the same time.

Although both laser treatment and vitrectomy are effective in reducing loss of vision and have high success rates, they do not cure diabetic retinopathy.

A person with proliferative retinopathy is always at risk of new bleeding and may need repeated courses of treatment to help protect his or her sight.

Other eye conditions linked to diabetes

Other eye conditions linked to diabetes include cataracts, glaucomaIncreased pressure within the eye (intraocular pressure), which leads to visual loss., rubeosis iridis, nerveBundle of fibres that carries information in the form of electrical impulses. palsies, asteroid hyalosis and ischaemic optic neuropathy.

Cataracts

High levels of sugar in the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. over a long period of time affect the aqueous liquid in the eye. This gradually seeps into the lens, producing a cataract - a clouding over of the lens, causing hazy or blurry vision.

The most common type of cataract is an age-related cataract that forms earlier in a diabetic patient than it would otherwise have done.

Glaucoma

People with diabetes are more likely than people who do not have diabetes to develop glaucomaIncreased pressure within the eye (intraocular pressure), which leads to visual loss..

This usually occurs when the pressure rises inside the eye, which in turn damages the optic nerveBundle of fibres that carries information in the form of electrical impulses. that carries images from the eye to the brain. In diabetic retinopathy there is also the added risk of new bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels closing off fluid flow in the eye and increasing eye pressure. This is called neovascular glaucomaIncreased pressure within the eye (intraocular pressure), which leads to visual loss..

Rubeosis iridis

In this condition there is severe ischaemiaInsufficient oxygenation to a part of the body due to poor blood supply. or narrowing of the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels to such a degree that new bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels form and grow over the iris in the eye.

If these then start to block the drainage system of the eye it gives rise to glaucomaIncreased pressure within the eye (intraocular pressure), which leads to visual loss. (raised pressure inside the eye), which may require urgent treatment to prevent blindness occurring.

Nerve palsies

Although uncommon, diabetes can sometimes damage the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. supply to the cranial nerves that are vital in normal eye movements. This can cause problems with eye movement that requires specialist assessment, although many cases resolve satisfactorily without requiring specific treatment.

Asteroid hyalosis

This condition causes tiny white specks in the vitreous fluid and usually has no symptoms. Unless it is very severe - when it may start to affect vision - the best treatment is usually to leave it alone.

Ischaemic optic neuropathy

This is a sudden loss of central and occasionally side vision, and is due to reduced bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. flow to the optic nerveBundle of fibres that carries information in the form of electrical impulses. at the back of the eye, caused by diabetic retinopathy.

Warning signs

If you have diabetes you should seek an urgent ophthalmological assessment if you have any of the following signs or symptoms: [2]

  • Sudden loss of vision
  • Sudden change in the quality of your eyesight
  • A painful eye
  • A pupil that reacts irregularly compared to the other eye
  • Sudden haziness of vision.
References: 
  1. Department of Health, 'National Service Framework Statement: Diabetic Retinopathy Screening'. 3 April 2008.
  2. National Health Service National Institute for Clinical Excellence. 'Type 2 Diabetes: the management of type 2 diabetes (update) 2008'. 2008a.
  3. Scottish Intercollegiate Guidelines Network. 'Guideline 55. Management of Diabetes, Section 6: Prevention of Visual Impairment'. Nov 2001.
  4. Younis N, Broadbent DM et al. Incidence of sight-threatening retinopathy in patients with type 2 diabetes. Lancet. 2003 Jan 18; 361: 195-200.
  5. Mohamed Q, Gillies MC, Wong TY. Management of diabetic retinopathy. JAMA, 2007 Aug. 22:298 (8): 902-16.