|
Medical Definition of Thelazia
1. The eye worms, a genus of spiruroid nematodes that inhabit the lacrimal ducts and surface of the eyes of various domestic and wild animals, but rarely man; a number of species have been reported from wild birds. Cyclic development occurs in muscoid flies; infective larvae emerge from the fly mouthparts while the fly is feeding on or near the eyes of the host. Origin: G. Thelazo, to suck Thelazia californiensis, a species occurring in the tear ducts, conjunctival sac, or under the nictitating membrane of dogs, coyotes, black bears, sheep, deer, jack rabbits, cats, and occasionally humans in the western and southwestern U.S.; heavy infections cause photophobia, lacrimation, eyelid oedema, conjunctivitis, and even blindness. Thelazia callipaeda, a species reported from man in Southeast Asia and California; the worm, embedded in a subconjunctival tumour or swimming in the aqueous humor after penetrating the corneoscleral limbus, causes pain, photophobia, and tearing. (05 Mar 2000)