health

Variations in the shape of the cornea or lens cause a person with astigmatism
to see images that are out of focus when they reach the eye’s retina*.
The retina is made of layers of light-sensitive cells at the back of the eyeball
that act like the film in a camera. The distorted image is projected onto the
retina and transmitted to the brain for processing through the optic nerve.
The first signs of astigmatism are determined by how severely the cornea
or lens is misshapen. In mild problems, people with astigmatism may
find that they have headaches or tired eyes at times or distorted vision
at certain distances. In severe problems, people with astigmatism may
find they have blurry vision that makes reading, playing sports, and other
activities difficult. Often the problem is discovered during an eye exam in
school, at the doctor’s office during a check-up, or when a parent notices
that a child is having trouble seeing clearly. Usually astigmatism does not
worsen as a person gets older.
In many people, astigmatism is accompanied by nearsightedness
(myopia) or farsightedness (hyperopia). In myopia and hyperopia, the eye
is also shaped incorrectly. In the former, the eye is long and egg-shaped
rather than round, or has a steep cornea, causing images to focus in front
of, rather than on the retina. In hyperopia, the cornea is too flat or the eye
is too short, causing images to focus behind the retina. Like astigmatism,
these conditions disrupt proper vision.