The eye is the organ by which obviouslysee. But if we stop to think about it more carefully, we realize the wonderful tool that has given us the nature. Just close your eyes for a moment to feel a sense of loss. The eye allows us totransfer energy of light with all its colors, that is the world in which we live, directly in the center of our brain and our consciousness. From birth we use our eyes in every activity for every day of our lives and unfortunately, those with impaired vision, knows the importance of this sense.But look a little more in particular how it's done.
In adults it can be compared to a small ping-pong with different diameters, with a weight of about 7 g and an internal voltage of 16 mmHg (called intraocular pressure or IOP by the acronym Anglo-Saxon Intra Ocular Pressure), due to the liquids contained in its interior. Suspended in the orbital fat and protected from orbit, owes its great mobility6 ocular muscles that allow you to move in all directions and coordinating collimating such movements with the other eye by providing a single clear image from the distance of a few centimeters (with stereoscopic vision), infinity. In short, a masterpiece of bioengineering.
At birth the eyeball is shorter than the norm (farsighted) and unlike its front (cornea and crystalline reaching already in 2 years, the normal size), grows rapidly in its rear portion (probably influenced not only by genetic factors as well as environmental factors and neurological) reaching the size of the adult (about 23,5 mm in a normal subject) in adolescence. The inharmonies this later development associated with that of the cornea leading to the creation of refractive errors (myopia , hypermetropia, astigmatism).
The eyeball, externally covered by a mucosa transparent, theconjunctiva, consists of three layers which from the outside inwards are: sclera, choroid, retina. Light waves penetrate into the eye through the firstcornea, which is the clear dome at the front of the eye, continuing through thepupil, the hole bounded by ' iris, that determines theeye color, are refracted by crystalline, transparent lens located behind the iris and the pupil. The light then passes through thevitreous, a gel which represents about 80% of the volume of the eye and whose alterations (floaters), are responsible for those gray dots that float in our view, to finally reachretina, specialized in a particular region of this, themacula where the light information are transformed into electrical signals, collected from optic nerveand transferred to the brain through theoptic tract.