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Soft Lenses

The role of soft lenses in keratoconus is limited because the soft lens drapes over the irregular corneal surface and the front surface of the lens assumes the same irregular surface as the cornea without trapping a fluid reservoir so the effective refracting surface is no improvement over the original corneal surface. There are some specially designed thicker soft lenses retain more of a rigid shape and may contribute to the liquid lens effect to some extent. There are designs being used for keratoconus, and they are helpful in mild to moderate cases.

RGP Contact Lenses

Rigid Gas Permeable (RGP or GP) contact lenses are primary option for correcting KC vision. The rigid lens masks the underlying irregular cornea and functions as the new refractive surface of the eye, with the tear film filling in the space between the back of the contact lens andthe front of the eye. “Rigid” defines the type of lens. “Gas Permeable” describes the lens material. There are many different RGP lens designs.

Without a Contact Lens	With a Rigid Contact Lens

"Piggy-backs"

This is a two lens system: an RGP lens worn on top of a soft lens. The RGP lens provides crisp vision and the soft lens acts as a cushion providing comfort.

Hybrid lenses

This is a lens design combination that has an RGP center surrounded by a soft peripheral “skirt”. Hybrid contact can provide the crisp optics of a GP lens and wearing comfort of soft contact lenses. They are available in a wide variety of parameters to provide a fit that conforms well to the irregular shape of a keratoconic eye

Scleral lenses

These are large diameter lenses that rest on the white part of the eye, called the sclera, and vaults over the cornea. The size can be an alarming prospect for some, but scleral lenses have many advantages. Because of their size, they do not fall out and dust or dirt particles cannot get under them during wear. They are surprisingly comfortable to wear because the edges of the lens rests above and below the eye lid margins so there is no lens awareness. The introduction of rigid gas permeable (RGP) materials has made this design more readily available.

This is a brief outline of the types of lenses available for keratoconus. There is no one “best” lens for keratoconus. The “best lens” is the one
that fits your eye, corrects your vision and is comfortable to wear. Rely on an experienced KC lens fitter to select the best for you, but there is no reason why you should not input into the discussion. Contact lens fitting for keratoconus is part science and part art. A great deal of patience is required both on the part of the fitter and the patient.

For instructional videos about the care and handling of GP lenses visit this web site.