Astigmatism is a specific type of refractive disorder. If you
are either near- or far-sighted, that means that your eye either
focuses light too far in front of or behind your retina. When
you have astigmatism, it means that your eye has an irregular
shape, and as such, focuses light to multiple points. It is
possible to have astigmatism and myopia or hyperopia, resulting
in a corrective lens with two differing powers in the lens.
Astigmatism correction needs to be aligned at a certain angle,
or "axis" to properly correct your vision. Standard contact
lenses can move or rotate on your eye without changing your
vision. Astigmatism lenses are specially weighted to ensure that
they sit on your eye a certain way. Because of this,
astigmatism-correcting, or "toric" contact lenses are generally
more expensive than standard or "spherical" contact lens. A
bifocal lens corrects for "presbyopia", a condition in which the
lens of the eye looses elasticity, making it harder to shift
focus for clear near vision. There are