Corneal ring implants.
D002983:Clinical Competence; D003406:Credentialing / Q000592:standards*; D006282:Health Personnel / Q000193:education; D006801:Humans; D007910:Lenses, Intraocular; D008504:Medical Staff Privileges / Q000592:standards*; D009885:Ophthalmology; D014481:United States