There are several soft contact lens products on the market designed with keratoconus and irregular coreas in mind. One of the latest innovations is the Kerasoft IC design which has gone a long way to improving this wearing modality for the keratoconus patient. Certainly in mild to moderate cases these lenses can be very successful. Their major advantage over other modalities is on eye comfort, however in some cases this can be at the cost of crisp vision.
Due to the nature of "soft" lenses they drape over the corneal curvature and, therefore, take on the ectasia to a degree. In the past soft keratconic lenses have been designed to be relatively stiff to act like an RGP lens and create a tear lens which counteracts the irregularity and astigmatism. The Kerasoft, however, does not try to mask the astigmatism in this way, it aims to regularise the astigmatism and as such is a much "softer" lens. The presence of high levels of astigmatism means that the fitting has to be stable in order to achieve a good level of vision. There can be a small compromise in the crispness of the vision over RGP/hard lens designs but this can be often outweighed by the comfort of the lenses and ease of handling. These designs can be overlooked in severe cases, however, it is the authors opinion that these lenses should be trailed initially to rule out their effectiveness. The advantage of lens comfort and lower risk of corneal abrasion is too great to be overlooked. |
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Irregular cornea specific soft lenses
Keratoconic designed astigmatic soft contact lenses.