Lasers may be increasing threat to the eye and the retina

An article in the New York Times by Christine Negroni refers to the increasing threat to vision and damage to the retina, by increasing access to the green laser.

Eye doctors around the world are warning of increasing number of cases of teenagers who suffer permanent eye damage while playing with high-powered green laser pointers.

The pointers, which have also been implicated in a ninefold increase over five years in reports of lasers’ being aimed at airplanes, are easier than ever to order online, even though they are 10 to 20 times as powerful as the legal limit set by the Food and Drug Administration.

A recent case highlights the problem: A high school student complained of a blind spot in his left eye, when a friend waved a green laser pointer in front of his face. The damage, as diagnosed by a retina specialist, was found to be severe and is not likely to completely heal, which means the high school student may end up with a permanent damage to his vision. The same retina specialist found out that the laser put out 50 milliwatts of power, 10 times more than the F.D.A. limit. And as he investigated his patient’s case, the doctor went online and bought a 100-milliwatt pointer for $28 (about Rs 1255) , and was hardly able to believe that he could buy an even more stronger laser without any controls or checks in place.

Like household lights, lasers are measured in watts, but the similarity ends there. A 100-watt incandescent bulb produces about five watts of visible light; the five-milliwatt laser is only one-thousandth as powerful. But because the light from a bulb is diffuse while a laser beam is concentrated, the effect of five milliwatts on the eye is 10,000 times as intense, according to laser experts. (For technical information on lasers, click here.) It also does not help that the eye tends to focus and intensify the laser, causing even more damage to the main part of the retina, the macula or the fovea, which is the center of the retina. The darker pigment present in the region absorbs the light as heat, quickly raising the temperature of the retina.

Some experts feel that the sale of laser pointers more than one milliwatt should be banned to the general public, since the stronger laser put people at risk of permanent visual impairment by the criminally minded or those who are unaware of the risks.

F.D.A., in its update, warned that a higher-powered laser gives less time to look away before injury can occur, and as power increases, eye damage may happen in a microsecond. One company that has come under scrutiny from the FDA is Wicked Lasers from Hong Kong.

Several laser experts feel that the enforcement of regulations is insufficient and ineffective. But any new restrictions being put in to contain the availability of such lasers will certainly meet resistance from the large community of laser enthusiasts, including those who use them professionally (like contractors and astronomers) and hobbyists.

Earlier, red lasers were used as laser pointers, Now, green lasers are more commonly used. But green lasers are also more dangerous. Green is more easily absorbed by the retina than red, so it requires less exposure to cause damage.

As a recommendation, please do not allow lasers to fall into the hands of unsuspecting children, who may find it easy to point the laser light at others, which can potentially be permanently damaging. Also, educate everyone who uses laser pointers to be more careful, including colleagues at work, who have the tendency of using the laser pointer during presentations, and who have the tendency of sweeping their hands around with the laser pointer turned on!