Retina

É the “film” Eye, a veil of nervous tissue transparent (thick by 500 μ in the periphery up to the 250 μ at the level of fovea) (1 "Μ" the micron, e` pari a 1 thousandth of a millimeter), that covers the internally choroid and which transforms the light information into an electrical signal which is then conveyed, via the optic nerve and the optical radiation, to the cerebral cortex dedicated to vision, in the occipital region (calcarine area).
It’ consists of several layers of cells stratified into horizontal cells, bipolar, amacrine and ganglion, some of which are specialized in the processing of the light signal into electrical signal calls photoreceptors that are the cones ed i rods. The first are approximately 6,5 million located in the fovea and allow clear vision and color perception, while the rods, cells are specialized for night vision (a basse luminanze, practically in white / black), are approximately 120 million and are distributed around the fovea, in the remaining retina and transmit information from the remaining visual field. There are three types of cones deputies to the perception of the three primary colors (red, yellow and blue) and how the rods, are oriented towards the inner part of the eye so that a beam of light, before stimulate a photoreceptor, penetrates all retinal layers, until you reach the 'pigment epithelium (membrane that is part of the retina with functions of nutrition and barrier, very rich in melanin) which allows to filter and absorb the incident light avoiding the phenomena of reflection of light inside the eye. Vascular diseases, inflammatory and infectious diseases of the retina are called retiniti, while its degeneration mainly affects the area Macular in senile età. The degeneration devices retinal and retinal detachment will be treated in a depth charts in being updated.