Nearsightedness

If you can see objects nearby with no problem, but reading road signs or making out the writing on the board at school is more difficult, you may be near- or shortsighted.

Your eye care professional may refer to the condition as myopia, a term that comes from a Greek word meaning “closed eyes.” Use of the word “myopia” for this condition may have grown out of one of the main indications of nearsightedness: squinting to see distant objects clearly.

Myopia is not a disease, nor does it mean that you have “bad eyes.” It simply refers to a variation in the shape of your eyeball. The degree of variation determines whether or not you will need corrective eyewear.

What causes nearsightedness?

Myopia most often occurs because the eyeball is too long, rather than the normal, more rounded shape. Another less frequent cause of myopia is that the cornea, the eyes’clear outer window, is too curved. There is some evidence that nearsightedness may also be caused by too much close vision work.

How does myopia affect sight?

Our ability to “see” starts when light enters the eye through the cornea. The shape of the cornea, lens and eyeball help bend (refract) light rays in such a manner that light is focused into a point precisely on the retina.

In contrast, if you are nearsighted, the light rays from a distant point are focused at a place in front of the retina. As the light will only be focused in that one place, by the time it reaches the retina it will have “defocused” again, forming a blurred image.

Who is affected by nearsightedness?

Myopia usually occurs between the ages of 8 to 12 years. Since the eyes continue to grow during childhood, nearsightedness almost always occurs before the age of 20. Often the degree of myopia increases as the body grows rapidly, then levels off in adulthood.

During the years of rapid growth, frequent changes in prescription eyewear may be needed to maintain clear vision.