The greater a laser pointer's output power, the more likely it will cause serious eye injuries, burn skin and temporarily impair the vision of pilots or drivers. That much is clear.
But judging the safety of that laser pointer in your desk drawer or in your kid's hand isn't simple.
"The consumer is in a difficult position," said Daniel Hewett, health promotion officer at the U.S. Food and Drug Administration's Center for Devices and Radiological Health, the agency tasked with enforcing the rule for products that emit radiation.
As power increases above five milliwatts, the time margin for safe exposure decreases and permanent eye and skin damage can occur quickly. However, the output power of laser pointers is not immediately apparent to the user. Laser pointers often lack appropriate labeling or are mislabeled, and definitive testing of individual pointers is beyond the reach of the average consumer.
The FDA does offer advice to help consumers identify which laser products might be dangerous and how to use devices safely. The agency is making laser safety awareness a priority just as a new study has shown that even the briefest exposure to high-powered blue handheld laser products can cause serious eye injuries.
Researchers have concluded that the wide availability of these devices, which are often marketed as toys, could lead to an epidemic of eye injuries, according to a study recently released by Ophthalmology, the journal of the American Academy of Ophthalmology.
If a laser with less than five milliwatts of output power is directed at someone's eye, that person can blink or turn away without suffering an eye injury. However, the natural protective mechanisms of the eye – such as the blink reflex – are ineffective against lasers with an output power greater than five milliwatts, and severe retinal damage may occur, even after momentary exposure.
Here's what the FDA advises:
- Never aim or shine a laser pointer at anyone.
- Don't buy laser pointers for your children.
- Before purchasing a laser pointer, make sure it has the following information on the label:
- a statement that it complies with Chapter 21 CFR (the Code of Federal Regulations);
- the manufacturer or distributor's name and the date of manufacture;
- a warning to avoid exposure to laser radiation; and
- the class designation, ranging from Class I to IIIa. Class IIIb and IV products should be used only by individuals with proper training and in applications where there is a legitimate need for these high-powered products.
The problem, said Hewett, is that the products sometimes lack labels or have inaccurate labels. He said about 60 percent of the sampled laser pointer products that the FDA tests are overpowered compared with what the label says. Those pointers may be powered in the 10s or 100s of milliwatts.
He also said some labels are too vague to be of any value. "We've seen one labeled 'less than 1,000 milliwatts,"he said. "A consumer may not know what that means."
Is your laser pointer overpowered?
Ideally, consumers could buy a laser pointer with the certainty that it's powered under five milliwatts. Amazon is trying to make it tougher to sell mislabeled lasers by requiring that all the pointers on its site be backed up by a compliance test report. Hewett said, as far as he knows, Amazon is the only firm that has taken that step.
The FDA says that if you have a laser pointer that isn't labeled or if you don't trust the labeling, consider the following:
- If the pointer is small and runs on button batteries, its output probably is less than five milliwatts.
- If it's pen-sized and runs on AA or AAA batteries, it's likely to be more powerful and may exceed five milliwatts.
- If it's flashlight-sized and runs on a cluster of AA or AAA batteries or runs on lithium batteries, it likely exceeds five milliwatts.
- Pointers sold with battery chargers probably drain their batteries quickly and are likely to be overpowered.
- Some pointers are sold with a removable cap that spreads the beam into a pattern. If used without the cap, the beam becomes a single beam that could exceed 5 milliwatts.
- Look for keywords that sellers might use to indicate a pointer is highly powered without saying that it's over five milliwatts: powerful, bright, ultra, super, military, military grade, super bright, high power, ultra bright, strong, balloon pop, burn, burning, adjustable focus, lithium battery, lithium powered.
- Look for videos or photos that show the laser burning, melting, balloon popping or show a bright, well-defined beam of light
- Look for purchaser comments on websites that tout the brightness or power of the product.
Why blue and violet lasers can be more dangerous
The FDA also explains why blue- and violet-light lasers can be especially dangerous: The human eye actually is less sensitive to blue and violet. So, while a victim would react quickly to a red or green laser, that person may not blink or turn away as fast from an equally powerful blue or violet light, creating a greater likelihood of injury.
After witnessing a rise in the occurrence of eye injuries caused by these lasers and to better illustrate the dangers of these products, researchers in Saudi Arabia documented the case histories of 14 young males, ages 11 to 30, who sought treatment for these injuries from January 2012 to January 2013.
Each of the 14 patients in the study had sustained injuries to one eye. Four of the patients suffered a full-thickness macular hole, a break in the part of the eye responsible for detailed, central vision.
Other macular injuries documented in the study included hemorrhages in different retinal layers, a macular pucker (when cells proliferate on the surface of the retina, causing visual impairment), a retinal disruption and a cavity in the retina. Only four eyes (29 percent) improved spontaneously with increase in vision, whereas 10 eyes (71 percent) required intervention, including vitrectomy (surgery in which the vitreous gel in the eye is removed and an operating microscope and small surgical instruments are used to remove blood and scar tissue that accompany abnormal vessels in the eye).
"High-power handheld laser devices may lead to an epidemic of ocular injuries that requires attention at different levels," wrote the study's authors from the King Khaled Eye Specialist Hospital Collaborative Retina Study Group in Riyadh, Saudi Arabia. "The difference between these new high-power laser devices and the low-power pointers cannot be overemphasized and government action such as banning the importation of these high-power handheld laser devices, laws for assault or malicious intent and a general public awareness campaign may be warranted."