It contains millions of rod and cone
cells which convert light energy into electrical signals sent
to the brain via the optic nerve. The macula (6x7 mm) is
the tiny spot on the retina where finer detail focus occurs.
The fovea (1.5 mm) is just behind the macula where the highest
concentration of cone photoreceptors are concentrated.
Light rays are focused by the lens onto the fovea for straight
ahead vision and fine detail. The sclera is the tough outer
wall of the eye and the choroid is the thin spongy layer between
it and the retina filled with blood vessels.