Duke Karl was a well-known ophthalmologist. He was the brother of the Empress Elisabeth of Austria. In 1877 Karl-Theodor began practicing medicine in Mentone. He was often assisted by his wife Maria Josepha. In 1880 he opened an eye-clinic in his castle at Tegernsee. In 1895 he founded the Augenklinik Herzog Carl Theodor (English: Duke Charles Theodore Eye Clinic) in Munich; the clinic in the Nymphenburger Strasse remains one of the most respected eye clinics in Bavaria to the present day. Between 1895 and 1909 Carl Theodor personally carried out more than 5,000 cataract operations as well as treating countless other eye disorders.