An Ophthalmologist Can Advise You the Best Scleral Contact Lens for Your Specific Needs If you have had a problem in wearing the contact lenses or have been told that you cannot wear them because of the irregular cornea, then consult your eye doctor and ask about the scleral contact lenses. These large-diameter gas permeable (GP) lenses vault over the entire corneal surface and rest on the sclera (white) of the eye. Scleral contact lenses are more stable on the eye than the conventional GP lenses – because of the size they are less likely to dislodge from the eye. These lenses offer the same advantages that conventional GP lenses compared with soft contact lenses such as sharper vision, greater durability, easier handling and a small risk of complications. Functionally scleral contact lenses correct vision problems caused by keratoconus and other corneal irregularities by replacing the irregular cornea with a perfectly smooth optical surface. Different types of scleral contact lenses Scleral contact lenses are larger than the standard gas permeable (GP) contact lenses, having a diameter equal to or greater than that of the soft contact lenses. The diameter of the smallest contacts can be 14 mm, and the largest can be upto 17 mm. Even the smallest scleral contact lenses are designed to cover the entire corneal surface since the average human cornea size is approximately is 11.8 mm in diameter.