Woodcut of the head of a woman with a cross-eyed condition. Strabismus a visual defect in which one eye cannot focus with the other on an objective because of imbalance of the eye muscles. Appeared in Ophthalmodouleia by Georg Bartisch (1535-1607) a German physician. He began his medical career, at the age of 13, as an apprentice to a barber surgeon. He was considered a skilled practitioner of ocular medicine and surgery. His Renaissance manuscript on ophthalmic disorders and eye surgery, Ophthalmodouleia Das ist Augendienst (1583), discussed ocular diseases, surgical techniques, instruments, including woodcuts depicting diseases of the eye. Despite his skill as a surgeon, he was a superstitious individual, as he believed that magic, astrology and witchcraft played a significant part in medicine.