Have you ever wondered why some people seem to have eyes that don't look straight
ahead? Maybe you've noticed that sometimes their eyes go in different directions when
they're looking at an object or at you.
Let's find out why some eyes don't see straight and how kids with this problem
get help to fix it.
Why Are Some Eyes Not Straight?
Strabismus (say: struh-BIZ-mus) is the term used for eyes that
are not straight and do not focus on the same object. Eyes can turn in (toward the
nose), out (toward the ear), up, or down if the muscles that move the eyes don't work
right or if the eyes are not able to focus properly. Strabismus is also sometimes
called crossed eyes (when the eyes turn in) or walleye (when they turn out).
You may have heard someone describe an eye that is not straight as a lazy eye,
but that is not what lazy eye means. It means that a person's vision is weak or lazy.
The medical term for lazy eye is amblyopia (say: am-blee-OH-pee-uh).
Strabismus and amblyopia are closely related and often (but not always) occur together.
Sometimes strabismus can cause amblyopia, and sometimes it's the other way around
with amblyopia causing strabismus. When a kid has both conditions, it may be difficult
to say which came first.
The Eyes Have It!
So what happens when a kid has an eye that isn't straight? To understand, first
you need to know a little bit about the eye.
The eye is like a camera, and the back of the eye, called the retina,
is the film. Objects that your eyes see are projected onto the retina, and these pictures
are sent to the brain by way of nerve signals. The brain detects these signals, puts
them together to form an image, and that's how you see. It's amazing that it all happens
so quickly — in a split second!
When a kid has strabismus, the eyes don't focus together on the same object and
each eye sends a different picture to the brain. As a result, the brain might see
two images (double vision) or the object looks blurry.
Kids' brains are really smart, and they don't like getting two different pictures
instead of one. To fix the problem, the brain may ignore the picture coming from the
one eye so it gets only one clear image. By shutting off the bad eye in favor of the
good one, the bad eye gets weak or lazy (causing amblyopia), and without treatment
the bad eye might eventually even become blind.