Causes
Diabetic retinopathy is a complication of diabetes. Diabetes causes high blood sugar levels, which can damage blood vessels. The damaged vessels around the retina can leak protein and fats, forming deposits that can interfere with vision. The damaged blood vessels are also not as effective at carrying oxygen to the retina, which can also cause damage. In the advanced stage, called proliferative retinopathy, new blood vessels grow in the eye. However, they are weak and often burst, causing bleeding in the eye. The bleeding can cause scarring of the eye and damage vision.
Hypertensive retinopathy is a complication of high blood pressure. High blood pressure damages the blood vessel walls, causing them to thicken and narrow. This reduces the blood supply available to the retina, leading to retinal damage. Eventually, blood can leak into the retina, causing further damage.