Thelazia

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 humans; 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. [G. thelazo, to suck]

- T. californiensis a nematode 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 edema, conjunctivitis, and even blindness.

- T. callipaeda a species reported from humans in Southeast Asia and California; the worm, embedded in a subconjunctival tumor or swimming in the aqueous humor after penetrating the corneoscleral limbus, causes pain, photophobia, and tearing.

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The·la·zia thə-'lā-zē-ə n a genus of nematode worms that is the type of the family Thelaziidae and includes various eye worms

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The·la·zia (the-laґzhə) a genus of nematodes of the family Thelaziidae. Several species, such as T. callipaeґda and T. californienґsis, are eye worms parasitic in domestic animals.