Astigmatism
What is Astigmatism?
In normal, undistorted vision, the cornea (the clear window in front of
the eye) is smooth and equally curved in all directions. With
astigmatism, the cornea is "warped", meaning it curves more in one
direction than the other distorting or blurring vision for objects at
any distance.
Large amounts of astigmatism are usually inherited, present at birth and
frequently remain unchanged throughout life. Small amounts of
astigmatism can be acquired any time in life and are, in fact, very
common. It often does not require correction.
Treatment
Correction is not difficult if the distortion proceeds across the cornea
in a regular direction. Prescription glasses can often be ordered that
neutralize or off set the distortion to the cornea.
If, however, the distortion is irregular, only reshaping the cornea will
correct the problem. This is usually done through the use of hard lenses
or by replacing it with donated human corneal tissue. While hard lenses
are usually better than soft lenses for this correction, some special
soft lenses may be helpful to correct mild astigmatism. Large amounts of
astigmatism are not easily corrected with lenses as it may wobble on the
uneven surface of the cornea. In such instances, a special device called
a toric lens may be ground with a curve on the back surface which
stabilizes the lens on the cornea.
© Copyright by the Canadian Ophthalmological Society