Health A-Z

Medical Content Created by the Faculty of the Harvard Medical School


What Is It?

A person who is nearsighted has difficulty seeing objects in the distance, although he or she can see close objects well. Nearsightedness is also called myopia.

In some cases, nearsightedness is an inherited condition caused by an abnormally long eye, as measured from front to back. Because there is a longer distance between the cornea (the clear "window" that covers the front of the eye) and the retina (the light-sensitive layer at the back of the eye), images tend to focus in front of the retina, rather than on the retina itself.

In other cases, nearsightedness is the result of a mismatch between the length of the eye and the ability of the eye's lens to focus an image in the correct location. Again, this causes images to focus in front of the retina, resulting in nearsightedness.

Currently, nearsightedness is the most common form of vision problem in the United States, affecting an estimated 25% of Americans. In many cases, genetic factors play a role in the condition. Several generations of the same family can have the problem.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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