Diabetes is a disease that can cause changes in your eyes

The retina is the light-sensitive layer of cells at the back of the eye that converts light into electrical signals. The signals are sent to the brain which turns them into the images you see.

The retina needs a constant supply of blood, which it receives through a network of tiny blood vessels.

Over time, a persistently high blood sugar level can damage these blood vessels in 3 main stages:

• background retinopathy – tiny bulges develop in the blood vessels, which may bleed slightly but do not usually affect your vision

• pre-proliferative retinopathy – more severe and widespread changes affect the blood vessels, including more significant bleeding into the eye

• proliferative retinopathy – scar tissue and new blood vessels, which are weak and bleed easily, develop on the retina; this can result in some loss of vision