Rigid Gas-Permeable (GP) Lenses
The lens type most frequently used to
correct KC vision is a "rigid gas perme-
able" (GP or RGP) lens. Gas
permeable lenses have a number of features that
make them ideal for KC:
• They correct almost all the myopia and
astigmatism associated with KC.
• They provide excellent health to the
eye, because they allow the cornea to
"breathe" oxygen directly
through the lens material.
• They are easy to insert, remove and
• They can be custom designed for the
unique conical shape of each KC eye.
In addition to GP lenses, other contact
lens types have been successfully used in
certain cases of KC.
"Piggyback" describes the
technique in which a soft contact lens is placed on the
eye and a rigid lens is fitted on top of
the soft lens. For some people, this dual
lens system provides the best of both
worlds: the comfort of a soft contact lens
and the vision-correcting capabilities
of a rigid contact lens.
"Hybrid" is the term used to
describe a combination lens that incorporates a rigid
GP lens in the center, surrounded by a soft
peripheral "skirt." These lenses, while
challenging to fit, can provide a better
combination of comfort and vision than soft
GP lenses alone.
Scleral lenses are large-diameter GP lenses
that are designed to rest on the
sclera (the white part of the
eye). These lenses may be beneficial for individuals
with severe KC or who have difficulty wearing smaller GP lenses.
Contact Lenses for Keratoconus
is managed by many different contact lens designs. No one design is best for
every type of keratoconus. Since each lens design has its own unique
characteristics, the lens fitter carefully evaluates the needs of the
individual situation to find the lens that offers the best combination of
visual acuity, comfort and corneal health.