Scleral Contacts are a large-diameter gas permeable contact lenses. They are designed to sit over the entire corneal surface and rest on the whites of your eyes (sclera), rather than a conventional contact lens that just sits over the cornea. By doing this, Scleral lenses functionally replace the irregular cornea with a perfectly smooth surface to correct vision.
Additionally, a major difference between gas permeable lenses and Scleral lenses is the space between the cornea and the lens itself. This space serves as a fluid reservoir to provide comfort for people with severe dry eye that would otherwise not be able to tolerate contact lenses.