The retina extends from the edges of the ciliary body, lining the interior of the eye.

In the direct path of the photons which pass through the pupil without being refracted (i.e. without the light rays being bent) is a pit called the fovea centralis (“central pit”). This region has a high concentration of yellowish visual pigment and so is also called the macula lutea (“yellow spot”).

There are two types of photoreceptors, named after the distinctive shape of their modified cilia. In each case, the photoreceptor outer segments consist of stacks of membranes like a roll of pennies. The outer segment is connected to the cell body via a thin stalk.