Doctors from the Duke University Medical Center in Durham, North Carolina, report on the case of a nine-year-old boy who showed up at their hospital after being blinded by an adult playing with a handheld laser.
"Until he came in, no one had realised there was an actual injury and we saw the bleeding," Dr Cynthia Toth, one of the authors of the new report, told Reuters Health.
The high-power laser had passed through the boy's eye lenses and burst the blood vessels in the back of his eyes.
"This was a larger device that was sold as some toy, but it's a dangerous weapon," Toth said. "You can start a fire with the power that was coming out of that one."
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Toth is a professor of ophthalmology and biomedical engineering at Duke. She also has a long history of studying and working with lasers.
The high-power laser was made from a component of a dismantled home theater projector and purchased online.
Different classes of lasers
A laser, according to the US Food and Drug Administration (FDA), is a "powerful, targeted beam of electromagnetic radiation that is used in many products, from music players and printers to eye-surgery tools.
"The FDA regulates lasers, as it does other radiation-emitting electronic products, and separates them into classes and subclasses. Class 3a lasers include those typically used for pointing during presentations. Their power is capped at 5 milliwatts (mW) on the visible light spectrum under federal regulation. Class 4 lasers are the type used in industrial or medical settings and are an immediate hazard.
The laser used on the boy in the new report falls into class 4, according to the researchers. It produced 1 250 mW of power. The boy's vision eventually recovered after two months, Toth and her colleagues report in JAMA Ophthalmology. But other people are not so fortunate, Toth said.
Hole burned into back of eye
Within the past few months, other reports of eye injuries by lasers were published in other journals, Toth said. In one case, a laser burned a hole through the back of a person's eye. "I do think that higher power lasers are more available than they were in the past," she said. "For that reason, I wouldn't be surprised if there was an increase in the number of injuries."
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"The amount of damage correlates to the strength of the laser," Dr Stacy Pineles, assistant professor of ophthalmology and a retinal specialist at the Stein Eye Institute at the University of California, Los Angeles, told Reuters Health in an e-mail.
"Shorter wavelength lasers that are now available to consumers as described in this article are more easily absorbed by the retina and therefore can cause severe and sometimes permanent vision loss," Pineles, who was not involved in the new report, said.
People who work with lasers should wear protective goggles, she said. "Different types of lasers require specific goggles for maximum protection."
Toth said it's also important that people don't let children play with lasers of any type. "Even a so-called safe level can also be dangerous," she said, adding that people who think they are injured should see a doctor.
(Photo of boy playing with laser gun from Shutterstock)
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