When the blood vessels in the retina (the light sensitive tissue lining the back of the eye) swell, leak or close off completely – or if abnormal new blood vessels grow on the surface of the retina – it is called diabetic retinopathy.
Diabetic retinopathy symptoms may include:
Diabetic retinopathy usually affects both eyes. People who have diabetic retinopathy often don't notice changes in their vision in the disease's early stages. But as it progresses, diabetic retinopathy usually causes vision loss that in many cases cannot be reversed. The changes may be slightly different, depending on which type of diabetic retinopathy is the cause.
When blood sugar levels are too high for extended periods of time, it can damage capillaries (tiny blood vessels) that supply blood to the retina. Over time, these blood vessels begin to leak fluids and fats, causing edema (swelling). Eventually, these vessels can close off, called ischemia. These problems are signs of non-proliferative diabetic retinopathy (NPDR).
NPDR is the earliest stage of diabetic retinopathy. With this condition, damaged blood vessels in the retina begin to leak extra fluid and small amounts of blood into the eye. Sometimes, deposits of cholesterol or other fats from the blood may leak into the retina. NPDR can cause small bulges in ocular blood vessels, retinal hemorrhages, swelling of the eye and the closing of small ocular blood vessels. All these changes can affect vision.
As diabetic eye problems are left untreated, proliferative diabetic retinopathy (PDR) can develop. Blocked blood vessels from ischemia can lead to the growth of new abnormal blood vessels on the retina (called neovascularization), which can damage the retina by causing wrinkling or retinal detachment. Neovascularization can even lead to glaucoma, damage to the optic nerve that carries images from your eye to your brain.