Children are normally born farsighted and must exert focusing
effort (accommodate) even for distance. This causes a ciliary
muscle spasm followed by an eye elongation that reduces the
farsightedness and accommodative effort. This is nature's way of refining
the length of the eye so that excellent vision is the end result. The process is supposed to stop when only a little farsightedness
remains. It is constant close work which causes this process
to go too far and move the eye into myopia. If we did not learn to read, we would not become nearsighted
Is myopia preventable?
We believe that the answer is yes. If children use reading
glasses for reading and other close work as soon as the first
signs of nearsightedness appear, myopia can be prevented.
What is the difference between reading glasses and
distance glasses?
Reading glasses, also known as plus lenses, are convex in
shape. They move objects farther away and reduce accommodation
(focusing effort). Distance glasses, also known as minus lenses,
are concave in shape. They move objects closer and increase
accommodation.
What if an optometrist or ophthalmologist agrees
with the benefit of plus lenses but does not want to recommend
a strong enough lens to completely eliminate focusing when
reading?
Weak reading glasses are better than nothing and far better
than distance glasses for the child who is beginning to experience
myopia, but studies have shown that weak reading glasses are
usually not enough to prevent myopia.
How often and how long should plus lenses be used?
Plus lenses are used to protect our eyes from the unnatural
demands of modern life. They should be used for all PROLONGED
reading, computer use and other close work. When the school
years are over, the glasses can usually be put aside, since
the adult eye tends not to elongate further. The glasses can
be saved for middle age when the focusing ability diminishes
and they are needed for reading once again!
What if problems such as tired eyes are experienced
when using plus lenses?
Simply stop using them for a while.
If a child looks into the distance while wearing
reading glasses, won't everything seem even more blurred?
Yes. That's why they should be taken off when not reading.
Are bifocals a good alternative?
Bifocals are a combination of reading glasses and distance
glasses. The upper portion of the glasses contains distance
(minus) lenses and the lower portion contains reading (plus)
lenses. We do not recommend bifocals because the child is likely to
use the distance lenses in the upper half of the glasses for close work,
thereby further elongating the eye and causing irreversible
myopia. As an example, when using a computer, the child may use the lower portion to look at the keyboard, but will almost certainly use the upper portion to look at the screen.
Can myopia be prevented or improved by using eye
exercises?
No. The myopic eye is not in need of "exercise."
It is in need of relaxation. When we look into the distance,
our eyes are at rest. Focusing close is stressful for the
eyes.
For those who are already nearsighted, will the eyes get better?
Studies have shown that by relaxing the ciliary muscle spasm
through the vigorous use of plus lenses as much as one diopter of myopia can be eliminated. If the amount of myopia is greater than that, elongation of the eye has probably occurred. This cannot be reversed. Therefore, all of the myopia cannot be eliminated.
Many people don't mind wearing glasses. They think they are "cool." Why should they care about prevention?
Myopia leads to an increased danger of cataracts, glaucoma,
macular degeneration and retinal detachment. The more myopia
one has, the more that risk increases. It also leads people
to undergo risky corneal surgery to reduce the myopia. Many
people have lost their sight from such surgery.
Why do many people need stronger minus glasses year
after year?
Because each time they are increased in power they cause
more eye elongation and the need for stronger glasses.
Are plus lenses harmful in any way?
No. In fact they are sold in drug stores
to young and old alike without the need for a prescription.
How far should the eyes be from the book or computer or other close object when using the reading glasses?
When using the reading glasses, the child should keep the close object as far away as possible. It is best to keep the object far enough away so that it appears very slightly blurred, but still legible. As the eye tries to clear this slightly blurred image, the maximum relaxing force is applied to the ciliary muscle.
Can a child just use reading glasses bought at a drug store?
No. A professional should be seen to obtain individualized advice.
Drug store reading glasses are intended for adult-size heads.
The distance between the lens centers conforms to the usual
distance between the pupils of the adult head. If such glasses
are used by young children, who have a smaller interpupillary
distance, the "prismatic effect" of the lenses causes
increased convergence. This can cause problems such as double
vision and should be avoided. The distance between the child's pupils should be measured when the eyes are converging on a book. The centers of the eyeglass lenses should not be any farther apart than that distance.
