Retinopathy (Eye Damage)

Diabetic retinopathy is a degenerative condition affecting the capillaries (fine blood vessels) of the retina of the eye. (The retina is the layer that lines the back of the eye on which the 'seeing image' is formed.) Retinopathy is the most prevalent form of eye disease in diabetes and is the commonest cause of partial and complete blindness in the UK and other Western countries. Cataracts and primary glaucoma (i.e. glaucoma that develops independently) are both more likely to occur in people with diabetes. A form of secondary glaucoma can also occur as a result of advanced diabetic eye disease (a very advanced stage of retinopathy).

In essence, damage to the capillaries, which develops over a long period of time, causes these tiny blood vessels to enlarge and leak and then to proliferate. New capillaries grow in a disordered way in an attempt to compensate for, and replace, the ones that have been damaged, and this in itself causes further disruption of vision. Retinopathy occurs in both Type 1 and Type 2 diabetes but progresses differently in each form. Each type of diabetes carries a greater risk of a different stage in retinopathy than the other.

However, for both types of diabetes, two factors are known to be important with regard to retinopathy. These are the length of time that the person has had diabetes and the degree of glycaemic control. Other risk factors, both for incidence and progression, are hypertension (particularly important) and, possibly, age at diagnosis of diabetes. Also significant are proteinuria (protein in urine), extent of insulin requirement and duration of treatment time. Ethnic origin may be a factor and some studies have indicated that retinopathy is more likely to occur in particular racial groups.

There are several recognized stages of retinopathy.

Background Retinopathy
This is the first stage of the condition in which there is early damage to the blood vessels, causing them to enlarge and leak fluids and deposits onto the retina. When the retina is examined, there maybe evidence of waxy deposits, minute haemorrhages or aneurysms or a retinal blot, but this stage produces no symptoms. If the background retinopathy is detected, the person is usually monitored closely with further, regular eye screening. The level of glycaemic control may be discussed and intensifying insulin therapy may be an appropriate response. Also, a thorough physical check-up may be recommended in order to identify other possible problems, particularly high blood pressure and evidence of nephropathy.

Pre-proliferative Retinopathy
This is a more advanced stage, but one which still produces no symptoms. Examination of the eye is likely to reveal multiple small haemorrhages and 'cotton-wool' spots, along with other abnormalities but there is no formation of new blood vessels. There is a high risk of progression to the next stage of proliferative retinopathy and hence the person will normally be referred to a specialist ophthalmologist for an early appointment. An overall health review, including glycaemic control and checking for other possible complications, may also be recommended.

Proliferative Retinopathy
This is characterized by the growth of new blood vessels in response to growth factors released by parts of the retina that have been starved of their normal blood supply, due to previous damage. These new vessels are very fragile and are subject to bleeding into the vitreous body (the jellylike layer of the eye). There may be scar tissue formation causing a detachment of the retina, the appearance of 'floaters' (spots travelling across the field of vision), or a sudden painless loss of sight due to a larger haemorrhage into the vitreous body. Proliferative retinopathy threatens sight itself and it most commonly occurs in people with Type 2 diabetes. When detected, an immediate referral to an ophthalmology clinic follows without delay. The eyes are assessed and the person is given laser treatment to selectively destroy the parts of the retina that have been damaged. This halts the response to produce newvessels, while those that have already been formed degenerate without causing further harm. Laser therapy preserves the sight but it cannot restore what has already been lost. Several sessions may be needed to burn all the damaged areas of the retina.

See more diabetic complications information.