Diabetic retinopathy results from the effects of the systemic disease diabetes mellitus on the fine blood vessels in the retina, the light sensitive membrane which lines the inner surface of the back wall of the eye. Diabetes causes the blood vessels of the retina to either leak or to grow abnormally.

Incidence/age

Both Type 1 and Type 2 diabetes mellitus patients may develop diabetic retinopathy. The risk of developing diabetic retinopathy increases with the age of the patients and the length of time since the diabetes was diagnosed. It is estimated that diabetic eye changes occur to some degree in most patients who have been diabetic for more than 15 years. Only a very small percentage of these patients however will develop a problem with their vision.

What causes diabetic eye disease

The cause of diabetic retinopathy is incompletely understood. Diabetes, however, affects small blood vessels throughout the body causing closure and weakness of smaller vessels including those in the retina.
Signs/symptoms

Two main types of diabetic retinopathy occur.

In background diabetic retinopathy there may be leakage of fluid from the retinal blood vessels. The vision may be normal or the central vision may gradually become blurred.

In proliferative diabetic retinopathy abnormal blood vessels grow over the surface of the retina. These vessels may bleed leading to a sudden significant decrease in vision.

Complications of disorder

With proliferative retinopathy bleeding from the abnormal vessels can lead to tissue similar to scar tissue forming on the surface of the retina. This tissue may contract pulling the retina off the back wall of the eye leading to a retinal detachment.

Eye tests

A thorough examination of the eye is required to detect the early presence of diabetic retinopathy before a patient is aware of problems. The pupils are dilated with drops to allow examination of the inside of the eye.

Fluorescein angiography may be carried out to examine abnormal vessels on the retina in more detail. Fluorescein dye is injected into a blood vessel in the arm and it circulates throughout the body including the blood vessels at the back of the eye. Photographs are taken of the dye as it passes through the retinal blood vessels and will outline areas of leakage from blood vessels and abnormal proliferation of blood vessels.

An ultrasound examination of the back of the eye is carried out if bleeding has occurred within the eye preventing examination of the retina by the ophthalmologist.

Diabetic eye disease treatment

Medical treatment
In the majority of patients with diabetes treatment is not required and monitoring is all that is necessary. Strict control of the diabetes has been shown to slow the development and progression of diabetic eye problems.

Surgical treatment
Laser treatment is indicated for leaking blood vessels that are threatening the central portion of vision or to reverse the growth of new abnormal blood vessels.

If there is bleeding into the gel at the back of the eye which does not clear spontaneously then a vitrectomy may be carried out to remove the gel containing the haemorrhage from the back chamber of the eye and allow laser treatment to seal the bleeding blood vessels.

Retinal detachment surgery is indicated to reposition the retina in those rare cases which are complicated by a retinal detachment.

Outcome
Most diabetic patients do not suffer serious complications from diabetic retinopathy. Early detection and management of diabetic retinopathy is important however, to halt or to slow the development of potentially sight threatening problems. Diabetic retinopathy develops silently and an annual eye examination is important even when no symptoms are apparent