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00078_Field_78.txt
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1997-10-29
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RIGID BITORIC LENSES
For patients with high amounts of corneal toricity, over 2 D to
3 D, it is often necessary to fit them with a toric base curve rigid lens to match the toric surface of the cornea. A spherical base curve lens will not give a good physical fit.
A spherical base curve lens on a toric
cornea is like putting a section of a
basketball (spherical surface) on the
side of a football (toric surface)-they
will not match.
Toric base curve RGP lenses will also
have toric peripheral curves in order
to maintain a round optical zone and
give uniform peripheral clearance.
With a toric base curve the front
surface will have to be toric in most
cases to give the patient the proper
correction.