Effect of Diabetes on the eye: Diabetic Retinopathy
Diabetes Mellitus can affect the eye in many ways. A common complication is diabetic retinopathy where the small vessels of the retina (nerve layer) are affected. This is a major cause of blindness in developed countries, including Singapore. The incidence of diabetic retinopathy increases with the duration of diabetes, and patients with more than 10 years of diabetes have a high chance of developing some degree of blood vessel abnormalities and retinopathy.
The early stage of diabetic retinopathy is called background retinopathy. At this stage there are tiny blood spots, small microvascular changes (microaneurysms) and leakage of proteins and fat (exudates). In the early stages, the patient may not notice any visual symptoms.
As the retinopathy progresses, new abnormal vessels may develop (neovascularisation) on the surface of the retina or the optic nerve. These abnormal vessels may rupture and bleed into the eye and cause a sudden loss of vision. There may also be scarring and fibrosis which may cause traction and pull on the retina, resulting in retinal detachment and loss of vision.
If the macula (the central retina) is affected and there is leakage of fluid and swelling, patients may lose vision.
Patients with diabetes should go for regular eye checks to monitor for eye complications. Theeye specialist will carry out a thorough check which includes dilating the pupils so that he can examine the retina. Sometimes, a fundus flourescein angiography (FFA) is performed to evaluate the severity and extent of the disease.
In the early stage of diabetic retinopathy, the patient can be monitored regularly. In the more advanced stages of the disease, laser photocoagulation may be performed to slow down the progression and prevent loss of vision.
The laser treatment is performed as an outpatient procedure. It is often performed over several sessions. A laser beam is focused on the retina which induces areas of scarring. This helps to prevent disease progression and helps to close abnormal leaking blood vessels. A new treatment for macular oedema involves injecting special medicine into the eye.
In very advanced cases with bleeding in the eye, a surgical procedure called a vitrectomy may need to be performed to remove the blood and gel in the eye as well as to remove any scarred tissue.
Prevention and screening
Patients with diabetes should ensure good control of their diabetes and blood sugar levels with proper diet control and medication. This would help to prevent the onset and progression of diabetic complications in the eye. They should at least undergo a yearly eye examination to detect early changes of diabetes. Successful treatment of diabetic retinopathy depends on early detection and treatment.