Related to the eyes (5)
(Other definitions for optical that I've seen before include "Relating to vision and light" , "Relating to sight" , "To do with sight, perhaps an illusion" , "Concerning light" , "Concerned with view" .)
(Other definitions for optic that I've seen before include "Related to sight" , "Pertaining to the eye" , "What could measure the spirits" , "Spirit measuring device" , "Device for measuring out spirits" .)