Human Lens

A human lens located behind the iris. It usually refracts light waves to focus them as they travel through the lens and into the retina. There are two lenses in the human eye. There is the actual lens behind the iris and the cornea. The cornea also acts like a lens because there is a big difference of index of refraction when the light waves go through the air, to the cornea and to the aqueous humor, then when the light waves pass through the aqueous humor to the actual lens.

The human eye lens, mentioned in the internal structures of the human eye section, has many potential impairments such as Hyperopia or Myopia for example.

Hyperopia is also known as farsightedness and is caused because the lens is usually too flat.

On the other hand, Myopia is caused because the lens is too convex (curved).

Besides those two conditions, there is one more condition called astigmatism. Astigmatism is when the cornea (a second lens that is made for accomodation) is not shaped perfectly. There is a surgery for astigmatism, where lasers destroy individual cells in the cornea to get it perfectly shaped.