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. People with insulin dependent diabetes and who have suboptimal diabetic control are more likely to develop complications.


Types of Diabetic Retinopathy

  • Non-Proliferative 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).  This may occur in any part of the retina. In the early stages, the patient may not notice any visual symptoms. However, if these complications occur in the macula, which is the area that is responsible for central vision, then loss of vision can occur fairly early.


  • Proliferative Retinopathy: As the retinopathy progresses, new abnormal vessels may develop (neovascularisation) on the surface of the retina or the optic nerve. This occurs in the later stages and is known as Proliferative Retinopathy. These immature new vessels may rupture and bleed into the eye and cause a sudden loss of vision. There may also be scarring and fibrosis around the vessels and optic nerve which may cause traction and pull on the retina, resulting in retinal detachment and loss of vision.


Eye Examination

Patients with diabetes should go for regular eye checks to monitor for eye complications of the disease. The eye specialist will carry out a thorough check which includes dilating the pupils so that he can examine the retina. Sometimes the doctor may order a special photographic examination known as a fundus flourescein angiography (FFA) to evaluate the severity and extent of the disease. This investigation involves injecting a fluorescent dye into the arm and taking photographs as the dye enters the retinal vessels. This helps to show the extent and severity of  any areas of leakage, abnormal vessels or areas with insufficient supply of oxygen.


Treatment for Diabetic Retinopathy

In the early stage of Diabetic Retinopathy where there are mild retinal changes, 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 reduce the stimulus for further new vessel formation. It also helps to close abnormal leaking blood vessels and prevent new vessels from developing.

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 & 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. Other cardiovascular risk factors such as hypertension and high cholesterol levels should also be controlled. Successful treatment of diabetic retinopathy depends on early detection and treatment.