An excerpt from the book Taking
Care of Your Eyes.
When you are nearsighted (myopic), your vision is clear for
objects close to your eyes, but blurred for everything in
the distance. If a child cannot see the blackboard clearly
from the back of the classroom, chances are that he or she
comes in all degrees, from minimal to extreme. The more myopic
you are, the more blurred your distance vision, but the closer
up you can see clearly. In other words, your range of clear
vision is much closer to your eyes than if you weren't nearsighted.
Approximately 40% of the population has some myopia or will
develop it at some time in their lives.
commonly, myopia begins to appear gradually between the ages
of 8 and 12, though it can exist at birth or start to develop
as late as age 80. Myopia may be a nuisance but it is certainly
not a disease; most nearsighted people have perfectly healthy
eyes. Many "myopes" are happy to be able to see things clearly
up close without glasses. In fact, this ability can be a real
advantage, especially after middle age.
Sharp vision -- like the picture from a properly focused camera
-- depends on light rays coming to a focus on the retina (at
the back of the eye), just as light focuses on the film (at
the back of a camera). When light rays do not come to a focus
on the retina, vision will be blurred, and we say that a refractive
(optical) error exists.
is just one type of refractive error. The others are hyperopia
(farsightedness), astigmatism (uneven focusing), and presbyopia
(the inability to focus up close, which affects most people
around middle age). In myopia, the rays from distant objects
focus in front of, rather than on, the retina. Myopia is like
a camera that is in focus only for near objects; anything
in the distance is out of focus.
most cases, myopia is the result of a size variable, like
foot size or tallness. The myopic eye is larger or elongated
- too long for its optical power - which means its optical
power too strong for the eye. (You shouldn't think of nearsightedness
as "weak eyes.") Research suggests that ordinary myopia and
how fast it progresses during adolescence are determined by
heredity -- it tends to run in families. It is not caused
by using your eyes"too much" (you never hurt your eyes by
Does Myopia Get "Worse" as the Child Gets Older?
children's bodies grow, so do the eyes, which may cause a
gradual increase in myopia. And just as bodily growth can
be in uneven spurts, the changes in myopia may be similarly
uneven. During adolescence, the change can be rather rapid
and require a new, thicker eyeglass correction more than once
a year, but when body growth slows or stops (usually by age
18), the myopia tends to stabilize. There is normally no reason
to worry about the frequent changes in lens correction that
occur during adolescence. Almost never is there any real danger
to eyesight, and vision can almost always be corrected to
20/20 or better with eyeglasses or contact lenses.
There is an extremely rare type of myopia, called malignant
progressive myopia, which is a serious condition and leads
to gradual structural damage to the eye. This type needs regular
clinical evaluation. It is not related to ordinary myopia
and does not develop from ordinary myopia.
Correction for Myopia
eyeglasses or contact lenses provide a simple, effective way
to provide clear vision - by optically reducing the excess
power of the myopic eye. Wearing your correction will make
your distance vision clear. The more nearsighted you are,
the more you will want to wear your correction. Not wearing
it, however, will not harm your eyes in any way.