When you look at an object, light from the object passes through the cornea of your eye, then the lens and then the retina at the back of your eye. Nerve messages pass from the seeing cells (rods and cones) in your retina, down nerve fibres in your optic nerve to your brain. The messages are interpreted by your brain, which enables you to see. If the retina is damaged, a clear picture cannot be produced.
This is a companion discussion topic for the original article at https://patient.info/eye-care/retinal-artery-occlusion