About 95% has eyes among all living things on the earth now. Because the living thing survives, eyes are very advantageous sense machines.   The light that comes from the fronts of eyes goes into from the start cornea (Thus, reel it), and ..all bunch (.. arrives at the street retina ..) and the crystalline lens ().. ..glass body (.. ..glass)...
  It is complete, is colorless, transparent, and there no one to shut out light the other day.
  Moreover, it is a structure focused in a yellow spots part (pursud pan-) on the retina when light goes into eyes by a strong refracting power of the cornea and the crystalline lens.
  It actually becomes an opposite image, it reaches a large brain from the retina through the optic nerve, a inverted image is corrected, and the image that begins to be copied on the retina is caught as a sight.

Cornea
Transparent film in part of iris of the eye. Part in window where light is passed so to speak. It is on the boundary side of the external world and the eyeball, and thinness, and transparent colorlessness a film of about 0.5mm.

Strong film and conjunctiva
It is a strong film to cover the outside of the eyeball. A transparent thin film of conjunctiva puts it on the other side of on that and the eyelid. A thin film that is on the back side of the eyelid is called a conjunctiva. ..the secretion of mucus from the conjunctiva.. ..lachrymal gland
The conjunctiva and the cornea are enriched with tears secreted from), and the bacillus is flushed.
  It becomes it ....what dries this mucus and hardens.. the "and"...
Pupil
Part of "Hitomi" at center of iris of the eye. It becomes small in a large, bright point in a dark point.
Iris
Radiation part that encloses pupil. The size of the pupil is changed by shrinking and expanding, and the amount of light that catches one's eye is adjusted. The part of the pupil is called an iris, and the function that corresponds to squeezing the camera is possessed. And, the center is an expert as for light.
It is called, "Pupil (Very so)" ..the window to do and...
  It becomes brown with a blue pupil when it is few when the melanin pigment is included in the iris, and there are a lot of coloring matters.
Moreover, the melanin pigment has working that intercepts ultraviolet rays.