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There is no one design that is best for every type or stage of keratoconus. The “best lens” is the one that fits your eye, corrects your visionand is comfortable to wear. Rely on an experienced KC lens fitter to select the best lens for your eye.The needs of each individual is carefully weighed to find the lens that offers the best combination of visual acuity, comfort and corneal health 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.
Here is a brief outline of the types of lenses available for keratoconus:
Soft Lenses
The role of soft lenses for keratoconus vision correction has changed dramatically in the past year. The new soft lens designs combine the latest technologies in silicone hydrogel materials and complex mathematics to offer comfortable wear and excellent vision.
Older soft lenses draped over the irregular keratoconus cornea assuming the same irregular surface as the KC cornea without correcting the visual distortion caused by the irregularly shaped KC cornea.
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.
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To see an instructional video about RGP lenses visit the GP Lens Institute website.
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.
For more information about hybrid lenses
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.
For more information about scleral lenses visit the Scleral Lens Education Institute website