A scleral lens is a type of contact lens that rests on the sclera of the eyeball, creating a tear-filled vault over the cornea. Custom-made for each eye, a scleral lens is large and has a diameter between 18 and 20mm. It is designed to rest on the sclera, which is the white of portion of the eye, because it is less sensitive and stronger that the cornea. In comparison to corneal contact lenses, scleral lenses bulge outward considerably more. Scleral lenses are made of a highly oxygen permeable polymer. The space between the front of the cornea and the back surface of the scleral lens is filled with artificial tears, which fills in the surface irregularities of the cornea allowing vision to be restored in a comfortable manner.
Scleral lenses are designed to treat a variety of eye conditions, many of which do not respond to other forms of treatment. Scleral lenses may be used to improve vision and reduce pain and light sensitivity for people suffering from growing number of disorders or injuries to the eye, such as keratoconus, microphthalmia, corneal ectasia, Stevens-Johnson syndrome, Sjögren's syndrome, aniridia,and neurotrophic keratitis.