UPDATE AND CORRECTION 7/2/13: In the comments, Minnesotastan informs us that this is a model of an eye, not a prosthetic. Thanks, Minnesotastan!
This impressively detailed prosthetic eye may date to early Seventeenth Century Europe. Dr. Alun Withey, a medical historian at the University of Exeter, describes the development of ophthalmology:
Until the seventeenth century, eye complaints were troublesome and painful, and effectively seen as a form of disability. The virtual plague of ophthalmic conditions in early modern Britain is attested to by the ubiquity of remedies for eye complaints in remedy collections. Common were remedies for sore eyes, which were often treated (in line with the ‘doctrine of sympathies’) by using substances of a similar constitution to the eye. Remedies using snails were popular; one common example was to impale a garden snail on a pin and let the juice run into the eye. Another recommended using fresh goose dung, its gelatinous consistency resembling the watery eye. Yet another suggested the blowing of dried hen’s dung into the afflicted party’s eye just before they went to sleep.