(CBS/AP) John Matthews was going blind and had no idea why. Then specialists discovered that the Cedar Rapids, Iowa man had a raccoon worm living in his retina.
The tiny parasite may have been there for a month.
The worm, only 1/20 of an inch long, was "moving, eating the retina," says Matthews' doctor, James Folk. Specialists had to use a laser to kill it.
Matthews sought medical help after he noticed two spots obscuring the vision in his left eye.
Doctors in the ophthalmology department at the University of Iowa Hospitals and Clinics found the worm, and doctors shot two rounds of laser blasts into Matthews' eye to kill it
Matthews says he "could see it from behind, moving, trying to dodge the laser."
Doctors think he accidentally ingested the worm on a trip to Mexico or while turkey hunting.
Either way, Matthews was lucky. If doctors do not catch the parasite in time, it can kill a person.
MORE HEALTH CONTENT FROM CBS NEWS