Mexican doctors got quite the surprise as they peered into the eye of a 17-year-old boy. A flatworm was seen wriggling in and out of the teen’s eyeball.
By the time doctors saw him, the boy could barely see out of that eye. “He could not even see our fingers” when they were held just 1-foot away from his face, said lead author Dr. Pablo Guzman-Salas, who treated the patient at the Institute of Ophthalmology in Mexico City. Instead, the teen could detect only hand motions with his right eye, according to the report. (His left eye was not affected.)
An eye exam revealed serious damage. The teen’s right cornea was swollen and speckled with blood, and there were multiple holes in his iris — all because the worm was “moving freely in the eye,” Guzman-Salas told Live Science.
To access the worm, the doctors needed to surgically remove the lens from the teen’s eye , along with the vitreous humor, which is the fluid that fills the eyeball. During the surgery, the doctors noticed that the worm had also caused extensive damage to the retina, which is located at the back of the eyeball.
The worm was about 3 millimeters (0.12 inches) long and 1 mm (0.04 inches) wide, and was removed in several pieces, according to the report.
Parasitic worms like this can thrive within the human body and humans can attract these parasites via food or water. These types of cases are so rare that most often times it is simply a case of really, really bad luck.