Types of Vision

Emmetropia

If you are emmetropic it means you can
see well at a distance when your eyes are
at rest (when they are not accommodating
or trying to focus). Your eye is correctly
shaped so that the light rays focus (or
refract) on the retina in the back of the eye
as they should. This allows for a clear
image to be processed by the optic
nerve/brain and seen through the eyes.

Nearsightedness

If you are nearsighted it means that you can
see well up close, but things at a distance
appear blurry. Nearsightedness occurs
when the cornea (the front of the eye) is too
steep, or the eye is too long, and the light
rays focus in front of the retina, rather than
on the retina as they should. This condition
can be corrected by glasses, contacts, or
laser vision correction.

Farsightedness

If you are farsighted it means that you
might see well at a distance by focusing
the eyes, but as focusing diminishes with
time both near and distance vision become
blurry. Farsightedness occurs when the
cornea (the front of the eye) is too flat or
the eye is too short, and the light rays
focus behind the retina, rather than on the
retina as they should. This condition can
be corrected by glasses, contacts or in
some cases laser vision correction.

Astigmatism

If you have astigmatism it means that your
eye is not round, rather it is much like a
football, which causes some light rays to
focus on the retina and some to focus in
front or behind the retina. This visual
distortion can produce shadows, double
images, or ghosting. Often people will have
astigmatism combined with nearsightedness
or farsightedness. This condition can be
corrected by glasses, contacts or in most
cases laser vision correction.