Eye

Different living entities on earth possess different organs which are sensitive to light and in human being eye is a photo sensitive organ. Human eye has two major segments as anterior and posterior segments. In the anterior segment of human eye, iris, cornea, lens and ciliary bodies with distinguishing functions are included along with two chambers filled with fluids. Anterior chamber is the space between iris and corneal endothelium whereas the posterior chamber is the space between the frontal face and iris. In the posterior segment of eye retina, choroids, optic nerves and vitreous humor like structures are associated. The retina in the posterior segment is the structure where the light focuses. Rods and cons are the two photosensitive cells very similar in metabolic and structure but these are quite different in their functions.

Rod cells are responsible for vision in the dim light as these are highly sensitive to such lights. Rods cells are not capable of distinguishing different colors. On the other hand the cons cells enable to see in the light and also promote color differentiation. The image formation pattern in different organisms and in human the light rays enter the cornea and travel through pupil that is encircled by Iris. Light rays fall on the retina, which processes and changes incident light rays to the neuron signals by means of the rods and cones cells which gets transmitted via the optic nerves. These signals on reaching the occipital cortex undergo processing which is responsible for interpreting into images.