Corneal transplantation is the replacement of diseased tissue with healthy donor tissue in individuals whose cornea is deformed or has decreased transparency, resulting in decreased visual acuity. Medically known as keratoplasty, the most common causes are keratoconus, bullous keratopathy, corneal microbial ulcers, corneal disorders resulting from infections or accidents, corneal dystrophies, and hereditary corneal lesions.