Scleral lenses are large-diameter rigid gas permeable lenses that are used to treat patients with irregular corneas, when other treatment options have failed. The lenses are called “scleral” because they completely vault over the cornea and extend to sit on the sclera (the white outer wall of the eye).
Typically, scleral lenses are recommended to correct the vision of patients with irregular corneas caused by conditions such as keratoconus. Keratoconus results when the cornea of the eye thins and begins to bulge outward into a cone-like shape. Scleral lenses can also be used to treat patients who have disorders that affect the quality or quantity of tears needed to keep the surface of the eye smooth and healthy. Examples of these conditions include dry eye syndrome and Sjogren’s syndrome.
Because of their material, diameter and shape, scleral lenses offer certain advantages over corneal lenses. Most contact lenses rest exclusively on the cornea (one of the most highly sensitive tissues in the body) while sclera lenses rest primarily on the conjunctiva. The conjunctiva, which covers the sclera, is made up of soft clear tissue that is significantly less sensitive than corneal tissue. Scleral lenses protect irregular or damaged corneal tissue by trapping a reservoir of fluid behind the lens. They also allow for clearer vision by providing a smooth front surface through which light can enter the eye.