Laser pointers

In the period from 2000 to 2008, increasing attention has been paid to the risks posed by so called laser pointers and laser pens. Typically, sales of laser pointers is restricted to either class 3A (<5 mW) or class 2 (<1 mW), depending on local regulations. For example, in the US and Canada, class 3A is the maximum permitted, unless a key actuated control or other safety features are provided and in the UK and Australia, class 2 is the maximum allowed class. However, because enforcement is often not very strict, laser pointers of class 2 and above are often available for sale even in countries where they are not allowed.

Van Norren et al. (1998) could not find a single example in the medical literature of a <1 mW class III laser causing eyesight damage. Mainster et al. (2003) provide one case, an 11 year old child who temporarily damaged her eyesight by holding an approximately 5 mW red laser pointer close to the eye and staring into the beam for 10 seconds, she experienced scotoma (a blind spot) but fully recovered after 3 months. Luttrulla & Hallisey (1999) describe a similar case, a 34 year old male who stared into the beam of a class IIIa 5mW red laser for 30 to 60 seconds, causing temporary central scotoma and visual field loss. His eyesight fully recovered within 2 days, at the time of his eye exam. An intravenous fundus fluorescein angiogram, a technique used by ophthalmologists to visualise the retina of the eye in fine detail, identified subtle discoloration of the fovea.

Thus, it appears that a brief 0.25-second exposure to a <5 mW laser such as found in red laser pointers does not pose a threat to eye health. On the other hand there is a potential for injury if a person deliberately stares into a beam of a class IIIa laser for few seconds or more at close range. Even if injury occurs, most people will fully recover their vision. Further experienced discomforts than these may be psychological rather than physical. With regard to green laser pointers the safe exposure time may be less, and with even higher powered lasers instant permanent damage should be expected. These conclusions must be qualified with recent theoretical observations that certain prescription medications may interact with some wavelengths of laser light, causing increased sensitivity (phototoxicity).

Beyond the question of physical injury to the eye from a laser pointer, several other undesirable effects are possible. These include short-lived flash blindness if the beam is encountered in darkened surroundings, as when driving at night. This may result in momentary loss of vehicular control. Lasers pointed at aircraft are a hazard to aviation. A police officer seeing a red dot on his chest may conclude that a sniper is targeting him and take aggressive action. In addition, the startle reflex exhibited by some exposed unexpectedly to laser light of this sort has been reported to have resulted in cases of self-injury or loss of control. For these and similar reasons, the US Food and Drug Administration has advised that laser pointers are not toys and should not be used by minors except under the direct supervision of an adult.