Myopia is a condition of the eye where the light that comes in does not directly focus on the retina but in front of it. This causes the image that one sees when looking at a distant object to be out of focus but in focus when looking at a close object. We correct myopia through the use of corrective lenses, such as glasses or contact lenses.
The corrective lenses have a negative optical power (i.e. are concave) which compensates for the excessive positive diopters of the myopic eye. Myopia is partly hereditary.
Myopia is sometimes classified by the age at onset:
Congenital myopia, also known as infantile myopia, is present at birth and persists through infancy.
Youth onset myopia occurs in the early childhood or teenage, and the ocular power can keep varying till the age of 21, before which any form of corrective surgery is usually not recommended by ophthalmic specialists around the world.
School myopia appears during childhood, particularly the school-age years. This form of myopia is attributed to the use of the eyes for close work during the school years.
Adult onset myopia
Early adult onset myopia occurs between ages 20 and 40.
Late adult onset myopia occurs after age 40