It is possible that some patients may not be good candidates for conventional contact lenses if they have unusually-shaped corneas. However, the great thing about this is there are so many different options available for hard to fit types of patients. If you have an irregularly shaped cornea, your regular glasses or even a standard contact lens may not provide you with the best vision. We have seen patients with vision acuity of 20/40 who were unable to be corrected by glasses. After they were fitted with gas permeable lenses, their vision improved to 20/20, which was incredible.
What are “hard to fit” contact lenses?
Contact lenses such as these are considered medically necessary. An eye doctor that specializes in contact lenses creates these specialty contact lenses based on parameters of a patient's cornea, such that it allows them to see clearly. It is amazing how these lenses provide such sharp vision.
One of the potential downsides of specialty contact lenses is that they are not always as comfortable as other contact lens modalities, luckily there are designs that provide the improved visual acuity without discomfort.
Medically necessary contact lenses options
- Piggybacking: The piggyback design of contact lenses is to put soft contact lenses over your cornea before putting a hard lenses on so that it creates a barrier between your cornea and the hard lenses, so that every time you blink, it is less painful because there are soft contact lens in between .
- Hybrid contact lenses: Another option is hybrid contact lenses. This means there are still rigid gas permeable lenses in the center, but then the outside of those contact lenses is constructed from a softer material so that it is more comfortable for the patient.
- Gas Permeable Lenses: Gas permeable lenses are rigid, which makes them an excellent choice for correcting vision even in cases of irregularly shaped eyeballs. However, they often require time to get used to, and some individuals may find them difficult to adapt to.
- Scleral Contact Lenses: Designed to vault over the whole corneal surface, these lenses rest on the sclera (the white part of the eye), completely replacing an irregularly shaped cornea with a smoother surface to correct vision problems. As they rest on a less sensitive part of the eye (the white part called the sclera), they are more comfortable than standard gas permeable lenses. Another benefit of the Scleral lens design is that they are much wider and therefore do not move around which reduces discomfort. Furthermore they have a pocket for saline, which makes these lenses the ideal solution for someone with an irregular cornea who also suffers from dry eye.
