What causes myopia?
When the eyeball is too long.
With myopia, objects at close distance appear clearly, and on the other hand at far distance they appear blurred. The reason for this is that incident light rays are focussed not directly on the surface of the retina but before it since the eye-ball is too long. The longer the eye-ball the weaker the eye sight - that is the person is short-sighted and distant objects appear blurred.

How to treat short-sightedness?
Treatments for a life without glasses
For the correction of myopia there are surgical possibilities within the cornea (cornea resp. Laser treatment) and the eye lens ( lens treatment):
With the laser treatment, tissue of the cornea is eliminated in order to compensate the length of the eye-ball. This requires a certain thickness and stability of the cornea.
With the lens treatments, an artificial lens is inserted in order to alter the refraction behaviour. Lens treatments allow the compensation of very substantial visual defects as there is no limitation regarding the removing of corneal tissue.
Depending on the kind of visual defect, there are several treatment possibilities: