CNN reports that Thornton had her tooth implanted in her eye to function as a base to hold an artificial lens. Thornton lost her sight secondary to corneal scarring that resulted from Stevens-Johnson syndrome in 2000 and she has been living in darkness for the last 9 years. Her procedure is called a modified osteo-odonto keratoprosthesis (MOOKP). Try pronouncing that three times.
As technology advances medicine, perhaps this procedure won't require a tooth in the future. New synthetic materials will emerge. Maybe we'll even see some form of an artificial eye in the future.