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In the United States, the Food and Drug Administration (FDA) regulates laser products. The FDA classifies lasers as class 1 through 4 based on type of light emitted and the hazard posed by this light. The laser radiation in class 1 lasers is typically confined to the product and considered to be low hazard, an example would be laser printers or CD players. Class 2 products emit less than 1 mW of power of visible laser light, an example would be a bar code scanner. The majority of commercially available laser pointers fall under class 3a and have a limit of 5 mW of power. Both class 2 and 3a lasers are considered relatively safe because eye exposure leads to the blink reflex which helps prevent damage by limiting the exposure time of laser to 0.15 to 0.25 seconds. It is important to note, however, that injuries with class 3a lasers have been reported when these lasers are not used in a responsible fashion. Class 3b (maximum output power: 5–500 mW) and Class 4 (maximum output power: > 500 mW) laser devices serve industrial or specialized purposes and are extremely dangerous because they can cause severe injury with minimal exposure times. The blink reflex is ineffective in preventing retinal damage with such lasers. Moreover, the cornea and lens focus laser radiation onto a small spot on the retina, increasing the exposure risk. High-powered lasers are used for research, industrial, and medical purposes. Laser safety precautions including laser eyeglasses, protective housings, and safety training help limit occupational exposure. Nonetheless, there are many reports of hazardous laser use by laypersons, improperly trained operators, and malicious users. Use of lasers in lighting shows has been reported to cause ocular injury. Children are an especially vulnerable population and may be the victim of laser accidents because they are unaware of laser safety and find laser pointers curious and attractive (▶ Fig. 83.1a). Low-cost, high-powered lasers (up to 1,200 mW) have become popular in recent years and have been relatively easy to obtain via the internet; these lasers have potential for retinal injury and cases of such have been reported. Photocoagulation, photodisruption, and photochemical interaction are all possible mechanisms of damage to the retina. Damage varies depending on the wavelength, exposure time, power, and the location of exposure. Blue light lasers are considered relatively more dangerous than green or red light laser given their shorter wavelengths which are more readily absorbed by the retinal pigment epithelium (RPE), though retinal damage and injury can occur at all wavelengths of light.

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