GRANTS PASS, OREGON — A woman from Oregon got the shock of her life after discovering what was really irritating her eye: worms.

CNN reports that thelazia gulosa are parasitic worms typically found in cattle. They live on the surface of the eyeball, and produce larvae that stay in the tears.

Face flies that feed off the animal's eye secretions ingest the larvae, which develop into a more advanced stage while in the flies' digestive system.

The worms can enter a human host when an infected fly lands close to or in a person's eye.

So far, only 10 other cases of eye worms have been reported in the U.S., with none caused by thelazia gulosa until now.

Eye worms can be killed with anti-parasitic medicine, but may cause scarring. As such, patients are advised to just monitor the eyes and remove any worms.

The parasites have been known to cause vision loss and blindness in animals, but fortunately not in people.