Alex Raasch, age 10, of Utica, N.Y., for his question:

WHY ARE SOME OF US NEARSIGHTED?

Nearsightedness is a defect of sight in which distant objects that should be clearly seen are blurred. Heredity is the most important cause of the defect.

Very few babies are born nearsighted. The defect usually develops in childhood and adolescence and sometimes progresses rapidly until about the age of 21. You are nearsighted because either your mother or father or both of them were probably nearsighted.  Doctors sometimes call this eye condition myopia. A nearsighted person's eyeballs are too long. When the eye brings distant objects into focus, the image falls too far in front of the retina to produce a sharp picture. To correct this, nearsighted persons often wear contact lenses or glasses with lenses thin in the middle and thick at the edges.

Nearsightedness cannot be cured. Vision should be kept as near to normal as possible by using properly fitted glasses