Some people, whose corneas are scarred and damaged undergo a procedure where their own cornea is removed and replaced with a donor cornea. The resultant corneal surface can often be somewhat irregular and a contact lens is often required to restore regularity and improve vision. With a hard contact lens, many people go on to obtain very good vision.
Lenses are usually fitted once the eye has stabilised as in the immediate first few months the corneal shape will change as the graft settles. The combination of a new cornea and contact lens can often give excellent vision to a previously poorly seeing eye.