Mayo Clinic ophthalmologists have found commercially available Class 3A green laser pointers can cause visible harm to the eye’s retina with exposures as short as 60 seconds. The findings will be published in the May issue of Archives of Ophthalmology.
Dennis Robertson, M.D., Mayo Clinic ophthalmologist, conducted investigations with a green laser pointer directed to the retina of a patient’s eye; the eye was scheduled for removal because of a malignancy. The green laser damaged the pigment layer of the retina, although it did not cause a measurable decrease in the visual function of the patient’s eye. Dr. Robertson believes that longer exposures could harm vision, however. He also warns about potential damage from higher-powered green laser pointers. "With the use of laser pointers that are more powerful than five milliwatts, there would likely be damage to the actual vision," he says. "Functional damage could occur within seconds."
Dr. Robertson does not advocate against use of green laser pointers; rather, he advocates against their misuse. "Green laser pointers are not a public health hazard at this time, but something people should be aware of," he says. "I’m raising concerns that people should be cautious when using green laser pointers not to point them at someone’s eye or face. It’s like how you use your knife -- carefully." While pointing out risks of green laser pointers, he adds, "This is a potential hazard to people’s eyes, but rarely is it going to be a practical hazard because the aversion reflex we have naturally will cause a person to blink or turn away from a laser light."
Green laser pointers are readily available in stores and on the Internet, according to Dr. Robertson. "Kids can buy these," he says. "They’re not strictly regulated." He adds that Class 3A green laser pointers are increasingly being used by amateur astronomers to pinpoint objects in the night sky and by the construction industry and architecture educators to point out details of structures in daylight. Dr. Robertson conducted the eye exposure test with a consenting patient two weeks before eye removal due to ring melanoma. The patient’s vision was 20/20, and the macular retina appeared healthy.
Dr. Robertson exposed the patient’s retina to light from a commercially available Class 3A green laser with an average power measured at less than five milliwatts: 60 seconds to the fovea, the center of acute vision; five minutes to a site 5 degrees below the fovea; and 15 minutes to a site 5 degrees above the fovea. Dr. Robertson had color photographs taken of the eye before and after exposure to the laser.
Dr. Robertson examined the patient’s eye 24 hours after laser exposure. He found retinal damage characterized by yellowish discoloration involving the pigment layer beneath the fovea and at the site of the 15-minute exposure above the fovea. Each of these sites developed a grainy texture within six days. Study of the eye tissue under a microscope also confirmed damage to the pigment layer in the laser-exposed regions.
Dr. Robertson has been interested in the effects of lights on the human eye during his career, testing operating room microscopes, lights used in the clinic, red laser pointers and now green laser pointers.
Previously, he determined red laser pointers to be quite safe. "I tested different powers up to five milliwatts and could not create recognizable damage in the human eye with the red laser pointers," he explains. "So, at least a transient exposure to red laser pointers’ light is only of trivial concern."
Dr. Robertson attributes the risk differential between red and green lasers to wavelength. "We know that the retina is infinitely more sensitive to shorter wavelengths," he says. "The green lasers appear much brighter to the human eye because of the shorter wavelength and can cause damage." Dr. Robertson says Mayo Clinic’s investigations have clearly demonstrated that green laser pointers can cause irreversible damage to the pigment layer of the retina.
More articles from Health and Medicine:
Proteins in migration: New insights into the mechanisms of Parkinson’s disease
24.05.2013 | Deutsches Zentrum für Neurodegenerative Erkrankungen e.V. (DZNE)
New insights contradict promising Alzheimer's research
24.05.2013 | VIB (the Flanders Institute for Biotechnology)
This morning at 05:45 CEST, the earth trembled beneath the Okhotsk Sea in the Pacific Northwest. The quake, with a magnitude of 8.2, took place at an exceptional depth of 605 kilometers.
Because of the great depth of the earthquake a tsunami is not expected and there should also be no major damage due to shaking.
Professor Frederik Tilmann of the GFZ German Research Centre for Geosciences: "The epicenter is exceptionally deep, far below the earth's crust in the mantle. Such strong ...
The Ring Nebula's distinctive shape makes it a popular illustration for astronomy books. But new observations by NASA's Hubble Space Telescope of the glowing gas shroud around an old, dying, sun-like star reveal a new twist.
"The nebula is not like a bagel, but rather, it's like a jelly doughnut, because it's filled with material in the middle," said C. Robert O'Dell of Vanderbilt University in Nashville, Tenn.
He leads a research team that used Hubble and several ground-based telescopes to obtain the best view yet of ...
New indicator molecules visualise the activation of auto-aggressive T cells in the body as never before
Biological processes are generally based on events at the molecular and cellular level. To understand what happens in the course of infections, diseases or normal bodily functions, scientists would need to examine individual cells and their activity directly in the tissue.
The development of new microscopes and fluorescent dyes in ...
A fried breakfast food popular in Spain provided the inspiration for the development of doughnut-shaped droplets that may provide scientists with a new approach for studying fundamental issues in physics, mathematics and materials.
The doughnut-shaped droplets, a shape known as toroidal, are formed from two dissimilar liquids using a simple rotating stage and an injection needle. About a millimeter in overall size, the droplets are produced individually, their shapes maintained by a surrounding springy material made of polymers.
Droplets in this toroidal shape made ...
Frauhofer FEP will present a novel roll-to-roll manufacturing process for high-barriers and functional films for flexible displays at the SID DisplayWeek 2013 in Vancouver – the International showcase for the Display Industry.
Displays that are flexible and paper thin at the same time?! What might still seem like science fiction will be a major topic at the SID Display Week 2013 that currently takes place in Vancouver in Canada.
High manufacturing cost and a short lifetime are still a major obstacle on ...
24.05.2013 | Life Sciences
24.05.2013 | Ecology, The Environment and Conservation
24.05.2013 | Physics and Astronomy
17.05.2013 | Event News
15.05.2013 | Event News
08.05.2013 | Event News