Myopia

[Roxy]

Does anyone know where I can find more information on Myopia (nearsightedness). I want to know why light rays focus in front of the retina and if this is genetic or not. This has to do with physics because of the light and how it moves. I need more detailed but simple information.

[Danger]

I have no idea what level of education you are at, and my knowledge of optics is limited. Consider this a space-saver until an expert shows up.
Long or short sightedness is basically an inability of the lens to reshape itself in the proper way. This can be due to poor condition of the focusing muscles, bad neurological input to those muscles, or a defect of some sort in the lens itself.
Lenses are essentially transparent crystalline protein structures. Anything (such as, alas, advancing age) that alters their flexibility will affect the ability to focus properly.

[Gamecubesupreme]

Concave and convex.

[KingNothing]

http://www.physicsclassroom.com/Class/refrn/U14L6e.html