<P> In the months leading up to the eclipse, many counterfeit glasses were put up for sale . Effective eclipse glasses must not only block most visible light, but most UV and infrared light as well . For visible light, the user should only be able to see the Sun, sunglint reflected off shiny metal, halogen bulbs, the filament in unfrosted incandescent bulbs, and similarly intense sources . Determining whether the glasses effectively block enough UV and infrared light requires the use of spectrophotometer, which is a rather expensive piece of lab equipment . </P> <P> The eye's retina lacks pain receptors, and thus damage can occur without one's awareness . </P> <P> The American Astronomical Society (AAS) said products meeting the ISO 12312 - 2 standard avoid risk to one's eyes, and issued a list of reputable vendors of eclipse glasses . The organization warned against products claiming ISO certification or even citing the same number, but not tested by an accredited laboratory . Another problem was counterfeits of reputable vendors' products, some even claiming the company's name such as with American Paper Optics which published information detailing the differences between its glasses and counterfeits . </P> <P> Andrew Lund, the owner of a company which produces eclipse glasses, noted that not all counterfeit glasses were necessarily unsafe . He stated to Quartz that the counterfeits he tested blocked the majority of harmful light spectrum, concluding that "the IP is getting ripped off, but the good news is there are no long - term harmful effects ." As one example, the Springdale Library in metropolitan Pittsburgh, Pennsylvania, accidentally passed out dozens of pairs of counterfeit eclipse glasses, but as of August 23 had not received any reports of eye damage . </P>

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