In myopia the distance between the cornea and the retina is greater than normal. A parallel beam that enters the eye does not focus on the retina, but in front of him.
Those with myopia see near objects clearly but far away objects appear blurred. With myopia, the eyeball is too long, or the cornea is too steep, so images are focused in the vitreous inside the eye rather than on the retina at the back of the eye.
The continuous increase during intramedullary axis of the eye during development is responsible for the increase in myopia observed in this period. The increase in myopia usually ends with adultness.
There is no physiological adaptive mechanism able to provide good distance vision in myopia. Even low degrees of myopia cause a significant reduction in distant vision and require correction with glasses, contact lenses or refractive surgery.