The retina is to the eye like film is to a camera. The retina contains all the sensory receptor for the transmission of light. It collects all the information and sends it to the brain. But the retina is also a part of the brain. The retina has two types of receptors, rods and cones. The rods function best in dim light; the cones function best under daylight conditions. There are many more rods than cones in the retina. Color vision is dependent on the integrity of the cones. The cones form a concentrated area in the retina known as the fovea, which lies in the center of the macula.

Damage to this area can severely reduce the ability to see directly ahead. The macula is the area of the retina that we use for our fine and straight-ahead vision. If the macula or fovea are damaged, a blind spot appears in the central vision. Rods are in the periphery of the retina, not in the macula. If these are damaged, it can result in night blindness, but with good vision for straight - ahead objects.