The incidence of diabetes is on the rise and it is now one of the leading causes of legal blindness amongst working age adults. Diabetes has the potential to affect almost all systems and organs of the body leading to vascular, neurological, heart and kidney diseases. Although diabetes sometimes causes early formation of cataract, the majority of its impact on vision is a result of the effects of raised blood sugar levels on the walls of the small retinal blood vessels called capillaries. This is known as “Diabetic Retinopathy” (DR).
Damage to the retinal capillaries may result in leakage of fluid from the blood-vessels causing swelling of the retina which we term “oedema”, or a loss of nutrition and oxygenation resulting in retinal cell death known as “ischaemia”. Chronic swelling of the retina may cause the deposition of fatty material or exudate in the retina and cause deterioration of the nourishing layer beneath the retina called the retinal pigment epithelium. Ischaemic damage can result in the formation of abnormal vessels on the surface of the retina (neo-vascularisation) which in turn can cause bleeding into the eye or contract to distort and even detach the retina from the wall of the eye. When neo-vascularisation has developed we say that a person has “Proliferative Diabetic Retinopathy”.
Role of Diabetic Screening:
Early retinal changes related to diabetes are usually asymptomatic and a person is only usually aware of the damage caused by the diabetes once the vision starts to become affected. By that time, it is often too late for treatment to be fully effective in overcoming visual loss. We therefore recommend regular screening for all patients with diabetes. Initially this is often done by photo-screening every 2 years, but once diabetic retinopathy is identified regular specialist appointments become necessary. Your doctor or diabetic specialist should arrange these checks for you.
Treatment for diabetic retinopathy:
Treatment is usually carried out if the disease is threatening or affecting the vision. Leaky blood vessels are either treated with laser or injections of special medicines into the eye called intravitreal injections. Retina affected by capillary occlusion is often treated with laser, or at times with injections. Your specialist will explain and discuss these options with you depending upon the type of disease process.
Vitreo retinal surgery for diabetic eye disease:
In late stages, neo-vascularisation caused by ischaemic diabetic eye disease can result in bleeding and scarring inside the back of the eye which blocks light from getting to the retina. This blood can be removed by vitrectomy surgery, and laser treatment is often carried out at the same time. The scarring from proliferative retinopathy can pull the retina off the back of the eye – tractional retinal detachment. Complex vitreoretinal procedures are possible to deal with this scar tissue and to reattach the retina. However once eyes get to this stage it is unusual to get good results from surgery and it is best by far to prevent retinopathy getting to this stage by maintaining excellent control of the diabetes and other risk factors such as high blood pressure, and by detecting retinopathy early through regular screening.