Billions of people around the world use vision-correcting lenses, and even more wear sunglasses for protection from the sun and – of course – for fashion. Although all prescription glasses are medical devices, they’re so ubiquitous that people rarely stop to think about how they’re made and tested. Yet, as with so many of the products that we use every day, accreditation and the global quality infrastructure play a critical role in delivering safe and functional products to consumers. Eyeglasses must be tested for a wide range of factors, everything from how much UV light passes through the lenses to whether the frame material could harm someone’s skin. These important tests are uniform across the industry thanks to a series of international standards.
A2LA’s role is to assess an organization’s ability to perform these types of standardized tests, which helps to ensure that they are producing consistent and verifiable results, which in turn produces a safer, more reliable product. A2LA accredits three testing labs for the world’s largest eyeglass manufacturer, Luxottica, which according to estimates by The Guardian sells nearly a billion lenses and frames each year. For a “20/20” perspective on the role of A2LA accreditation in everyday life, we’ve investigated some interesting examples of how eyeglasses are tested and why those tests are important to the end user.
When consumers purchase eyeglasses – especially prescription – they expect them to be able to hold up to frequent use and everyday mishaps. To test the durability of glasses, ISO has standardized more than a dozen testing methods associated with the sort of conditions that eyeglasses will be subjected to as they are used. Some of these tests are unsurprising, such as the “impact resistance” test, which – as the name suggests – subjects eyeglasses components to varying degrees of impact to assess how they perform. Other tests are less obvious but equally important to everyday use, such as the “resistance to perspiration” test. Human perspiration can degrade many types of material, and because eyeglasses are in frequent contact with the skin, manufacturers like Luxottica must understand how the various materials eyeglasses are made of will react to the compounds in perspiration, and how this affects the long-term usability of the glasses. Rest assured, the “perspiration” used in the test is a lab-made substance with a similar composition, not real human sweat. Materials are also subjected to tests that most people hope to never encounter in real life, like the “resistance to ignition” test, specified by ISO 12870. Of course, most eyeglasses are never put in scenarios where they are at risk of catching fire, but quality testing means understanding and accounting for as many variables as possible.
While eyeglasses must be durable, they also must be able to perform their primary function: helping people see. The physics of lenses, prisms, and light refraction are very complex, so having standardized testing methods across the industry is especially important when it comes to testing the lenses of glasses. Lens material must undergo both durability testing and testing to evaluate how light interacts with the lens. Testing of these qualities will be different for prescription versus non-prescription glasses, as well as for tinted versus clear lenses, and the differences in testing methods are also standardized by specific ISO testing methods. This testing ensures that the physical substance of the lenses will not break down when exposed to things like prolonged UV radiation, heat, and pressure from use, and that the light-transmission properties of the lens are appropriate for their intended purpose, whether prescription or otherwise.
Thanks to these standardized processes and the accreditation infrastructure that helps maintain product quality, eyeglass-wearers around the world can focus on the bright, clear world around them, rather than worrying about the handy little device they use to see it. For more information about Luxottica’s testing process, including some of the additional tests they have developed in-house, visit this article on the Luxottica quality lab, and for information about their general quality practices, visit this page.