Eyeworms and face flies in California

EYEWORM INFECTIONS are of economic importance in parts of Europe, Asia, and Africa, where about a dozen species of nematodes of the genus Thelazia inhabit and irritate the eyes of a variety of large mammals, including such domestic animals as cattle, horses, buffalo, camels, dogs, etc. The half-inch long worms live on the surfaces of the eye membranes, under the eyelids, or with some species, in the tear ducts or nasolachrymal canal. Ocular disturbances range from mild inflammation, commonly manifested by excessive tearing and photophobia, to occasional severe dysfunction, even blindness, of affected eyes.