Human Retina is an ultra-thin, soft and transparent sheet lining the inner surface at the back of the eye (like a thin light sensitive film), receives light and changes it into electrical signals which are then transmitted to the brain by the optic nerve. The most light-sensitive part of the retina is a tiny spot called the macula and this is where the vision is at its sharpest. Due to the laws of optics, the image formed on the retina is actually upside-down; it is the brain which adjusts it to make it appear the right way up.

Retina is the only part in the human body where blood vessels and their circulation observed live giving useful insights into many vascular processes. The pattern of vessels in each person is unique and this property is being increasingly utilized for identification through rapid retina scans at security points.

Study of retina and related pathology is a super-specialty subject requiring advanced training and experience after primary training as an ophthalmologist.