Laser protective eyewear.
The Food and Drug Administration's Bureau of Radiological Health has been conducting preliminary tests of laser protective eyewear. I believe that the test findings and actions being taken as a result may interest readers who buy or use laser eye-protective equipment. Protective goggles are used in certain laser applications to protect operators or bystanders from direct exposure to high radiation levels that could cause serious eye damage. Without protective eyewear and either fixed or portable shields of the same material, many injuries from laser exposure possibly would have occurred. The exposure of laser goggle materials to sufficiently high power or energy will cause damage in the form of melting, bleaching, bubbling, or shattering. However, some eye-safety products will thus fail after several seconds of exposure to laser beams of about 1 W, or a power density of about 6-12 W/cm . The FDA's Bureau of Radiological Health is concerned that not all eye protection users or buyers are aware of this fact. Manufacturers have been notified that some types of protective eyewear have failed during preliminary nonhuman testing in Bureau laboratories. The Bureau, however, has received no reports to date of human injury that might have occurred as a direct result of eye-protection equipment failures. Representatives of manufacturers and of professional groups met last October 5th at Bureau Headquarters in Rockville, Maryland, to discuss methods by which all products providing eye protection from lasers could be uniformly evaluated and appropriately labeled and the essential information disseminated to users and purchasers. The Bureau is working with manufacturers and other affected groups to develop criteria for the selection and use of protective eyewear in order to provide guidance for laser users and purchasers at the earliest possible date. Bureau laboratory personnel noted that protective goggles intended for use with helium-neon gas lasers, which normally have an output of a few milliwatts, have not shown signs of failure in the limited tests conducted thus far. Users who have occasion to employ these goggles when operating such low power helium-neon lasers should continue to do so. Individuals using protective goggles around high power lasers—for example, a multiwatt argon-ion laser—are advised to determine the failure points of their eyewear by contacting the manufacturer. In the event that the necessary information is unavailable, the eyewear should be tested by exposure to the most intense radiation against which it is expected to provide protection. Such a test should represent the worst case condition of exposure to the eyewear. The eyewear tested should be carefully inspected before it is returned to service. If the eyewear fails, operation of the system should be suspended until alternate means of personnel protection are provided. Laser protective eyewear should always be inspected prior to each use for signs of melting, bleaching, bubbling, or cracking. If any one of these signs is noted, the eyewear should be removed from service. Multiwatt lasers may commonly be found in universities, industry, and research laboratories and in medical applications. In some instances, servicing and alignment procedures for these lasers may result in possible direct exposure to a high power laser beam over a period of seconds or possibly minutes. Under these circumstances, the worker may risk serious eye injury if he is unaware of the failure point of the protective eyewear. The chance of eyewear failure increases as laser power and energy rise. Therefore, persons buying a laser product are urged to make certain that the presently owned eye-protective equipment will accommodate the power of the new product. It is the intention of the Bureau to develop, both from laboratory experience and from suggestions submitted, a set of criteria for the selection and use of protective eyewear in laser applications. Suggestions, comments, or information from readers that would assist the Bureau in establishing criteria and collecting eyewear failure data would be welcome. Communications should be directed to the Director, Bureau of Radiological Health, Food and Drug Administration, 5600 Fishers Lane, Rockville, Maryland 20852.