Eye Health

Updated 27 September 2017

You won't believe what lived inside this boy's eye

A tiny creature ended up costing a 17-year-old his sight. This parasite is rare, but well-known among ophthalmologists.

Many weird things have been found in the human body.

For one unfortunate Mexican teenager, an unwanted organism living in his eye led to what may be a permanent loss of vision, doctors report.

Severe eye damage

As published in The New England Journal of Medicine, an unnamed 17-year-old teen from a rural town in Mexico came to a hospital after suffering impaired vision and pain in his right eye for three weeks.

According to ophthalmologists Drs Pablo Guzman-Salas and Juan Serna-Ojeda, an examination showed an inflamed cornea, blood in the back of the eye, "multiple iris perforations" and damage in the other eye.

The cause?

"A flattened and mobile trematode [tiny flatworm] was seen moving freely" at the back of the eye, according to the doctors. The parasite was travelling – through holes it had made in the eye's iris – between the front and back portions of the eye.

How was the parasite treated?

The doctors said the teen was given praziquantel, a drug used to treat parasitic infections, and then underwent surgery to physically remove the worm, upon which even more damage to the eye was noted.

The worm "was removed in multiple pieces and [its species] could not be more specifically identified," said the physicians, who work at the Institute of Ophthalmology Conde de Valenciana in Mexico City.

Unfortunately, they said, six months later there was no improvement in vision in the teen's right eye.

How did he become host to the tiny worm? According to the physicians, the teen reported that he had not ingested foods that might contain the worm, nor had he swum in lakes where he might have contacted the creature.

Stool samples also showed no evidence of parasitic infection, they added.

Rare, but possible

Two eye doctors said such cases, while very uncommon, can happen.

"This is a rare, but well-known – to ophthalmologists at least – cause of vision loss," said Dr Jules Winokur, an ophthalmologist at Lenox Hill Hospital in New York City.

"Animals such as dogs, raccoons, skunks, fish or frogs can carry the parasite, and people can get infected either through ingesting the eggs or through contact with invasion through the skin," he said.

Dr Matthew Gorski is an ophthalmologist at Northwell Health in Great Neck, New York. He agreed that parasitic worms can affect the eye and cause major damage.

"Symptoms can range from mild to severe vision loss, blind spots, floaters and pain," Gorski said. "Treatment consists of a combination of laser surgery, oral medication, eye drops and eye surgery. Though rare, the effects of a nematode in the eye can be devastating to one's vision and quality of life.

Image credit: iStock


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Megan Goodman qualified as an optometrist from the University of Johannesburg. She has recently completed a Masters degree in Clinical Epidemiology at Stellenbosch University. She has a keen interest in ocular pathology and evidence based medicine as well as contact lenses.

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