Diabetes and The Eye

Diabetes mellitus or diabetes is characterized by increased levels of blood sugar, due to impaired production or reduced effectiveness of insulin.Patients with diabetes stand the risk of developing diabetic retinopathy due to changes in the blood vessels of the retina caused by poor glucose control. Blindness due to diabetic retinopathy is one of the leading causes of preventable blindness.

The retina is a layer at the back of the eye that senses light and sends images to the brain. In diabetic retinopathy the blood vessels in the retina become fragile and get blocked, leading to water collection (edema), lipid deposition, retina hemorrhages, and the formation of new vessels on the retina. Vision loss can occur due to the lipid and water deposition in the center of the retina (diabetic maculopathy), or due to bleeding inside the eye from new blood vessels(vitreous hemorrhage), or due to membrane formation over the retina which “pulls” on the retina (traction retina detachment).

Symptoms:
In the early stages there are no warning signs; the treatment works best in this stage if detected by a routine retina examination. In relatively advanced stages, the vision worsens gradually or suddenly, making reading or driving difficult. bleeding in the eye an lead to black spots or floaters or total blockage of vision. Persons with advanced diabetic retinopathy may find it difficult to:

• recognize faces from a distance or read bus numbers,
• read fine newsprint, bills, or low contrast text,
• write in a straight line,
• tolerate bright light or see in dim light,
• move about independently outdoors after dusk, and
• tell the time a wristwatch or read the print on an insulin syringe.

Need for early detection
The life expectancy of diabetic patients has increased with the availability of better medicines. However this means an increase in the incidence of diabetic retinopathy and its blinding complications. People with diabetic retinopathy are 25 times more likely to experience permanent vision loss than those with other sight-threatening ailments. Early detection and appropriate treatment can help prevent this. The only method of early detection is a regular and dilated retinal examination.

The recommended check-up schedule for a patient of diabetes with no diabetic retinopathy or its milder forms is:

• No or minimal retinopathy detected – once a year
• Mild to moderate non – proliferative diabetic retinopathy – between 6 to 12 months
• Moderate to severe non – proliferative diabetic retinopathy – between 3 to 6 months
• Very severe non – proliferative diabetic retinopathy- 2-3 months
• After photocoagulation – 1 to 6 months or as advised by the treating ophthalmologist.

Diabetic Retinopathy and Pregnancy
Pregnancy can increase the porogression of diabetic retinopathy. Hence pregnant woman with diabetes should have an eye examination every three months. Controlling blood sugar after the progression of diabetic retinopathy has less effect than controlling it in the initial years of the disease.