VISION
LIBRARY
Vision
Problems
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Keratoconus (Conical Cornea)
Poor vision that cannot be
corrected fully with glasses may indicate a condition known as
conical cornea or keratoconus. A rare condition, keratoconus
primarily affects people in their early 20's.
With keratoconus, the cornea, the "clear window" at the front of
the eye, may become thin and bow outwards. It is this irregular
distortion of the cornea that makes vision correction with glasses
less than optimal. This condition is typically progressive
and, therefore, laser refractive surgery would be contraindicated.
Vision correction with rigid
gas permeable lenses.
Mild to moderate keratoconus is
best corrected with rigid gas permeable contact lenses, which
provide a smooth surface in front of the cornea, making clear vision
possible. Because the lens is rigid, the tears between the lens and
the cornea form a 'liquid lens,' which smoothes the irregularities
of the cornea and makes clear vision possible again. Soft lenses,
which 'wrap' onto the cornea and take up its shape much more closely
than rigid lenses, are less successful at correcting keratoconus.
Corneal replacement surgery
may be necessary.
As keratoconus progresses, some
scarring of the cornea can occur. Eventually, contact lenses may no
longer be a successful treatment. Instead, the cornea may need to be
replaced surgically with a cornea of more regular shape. The
prognosis for corneal replacement surgery is generally very good.
