What is the name of a special contact lens used to treat keratoconus, featuring a soft outer lens and a rigid center?

The name of the special contact lens used to treat keratoconus that features a soft outer lens and a rigid center is known as a piggyback lens. This type of lens design combines the comfort of a soft lens with the optical clarity and visual correction of a rigid gas permeable (RGP) lens. The soft outer lens helps to cushion the RGP lens against the eye, providing enhanced comfort while the RGP portion maintains precise visual acuity for patients with the irregular corneal shape characteristic of keratoconus.

Using a piggyback lens can help manage the symptoms associated with keratoconus, such as distortion of vision, because it allows for a more stable fit and better overall vision correction compared to using either type of lens alone. This combination is particularly beneficial for patients who may struggle with discomfort from RGP lenses but still require the visual correction they provide.