The photoreceptors function by receiving information transmitted in the form of light. This information is then transferred to the optic nerves, to the brain through the optic disc, the spot on the lower outside of the retina.
The eye has two major cavities filled with clear watery liquid. One is located between the lens and the cornea, which is filled by the aqueous humor. The other is located behind the lens within the eyeball itself, just touching the retina. This is filled by the jellylike vitreous humor which constitutes the bulk of the eye. These liquids function as liquid lenses. Similar to the cornea and most parts of the eye, their function is to focus the light on the retina as liquid lenses. As said earlier, the retina houses the photoreceptors so that information can then be transferred to the brain for interpretation (Vander, et. Al, 2001).
The main question now is why is the retina placed as far inside the eye where information has to be passed from many different parts like cornea, pupil and liquid lenses, and when the speed of information transmission is very necessary especially in sensory organs. The last thought exactly answers the structural question of the anatomy of the eye. The retina is structured to layer the inner cavity of the eye to allow more surface area for information to be passed to the many different photoreceptors housed in the retina. The liquid vitreous humor helps disperse this light so that information can pass to the photoreceptors at a single instant instead of the light being directed at a single line and spreading to the many different photoreceptors in the retina. This means that the retina is perfectly structured for speed in the processing of information. It is also easier to vascularize this way than if the whole cavity is filled with retinal cells (Feinberg, 2004).
What is it with the retina that allows its function? The retina contains two types of .photoreceptors named for their shapes: 125 million rod cells and 6 million cone cells, the total of which accounts for about 70% of all body sensory receptors.