Gbex says:-Myopia or "nearsightedness" is a refractive defect of the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed.
Eye care professionals most commonly correct myopia through the use of corrective lenses, such as glasses or contact lenses.
It may also be corrected by refractive surgery, but this does have many risks and side effects. The corrective lenses have a negative optical power (i.e. are concave) which compensates for the excessive positive diopters of the myopic eye.