The retina is a thin disc-shaped layer of light-sensitive tissue on the back wall of the eye. Its job is to translate what we see into neural impulses and send them to the brain via the optic nerve. A retinal haemorrhage can be caused by hypertension, retinal vein occlusion (a blockage of a retinal vein), or diabetes mellitus (which causes small fragile blood vessels to form, which are easily damaged). Retinal haemorrhages can also occur due to shaking, particularly in young infants (shaken baby syndrome) or from severe blows to the head.
Retinal haemorrhages that take place outside of the macula can go undetected for many years, and may sometimes only be picked up when the eye is examined in detail with an ophthalmoscope. However, some retinal haemorrhages can cause severe impairment of vision.