Which type of lenses is known not to meet safety standards?

Glass lenses are known not to meet contemporary safety standards primarily due to their propensity to shatter upon impact. Unlike plastic and polycarbonate lenses, which are designed to be more impact-resistant, glass lenses can break into sharp shards, posing a significant risk of injury to the eye. As a result, they are often less suitable for use in environments where safety is a concern, such as in industrial settings or for individuals participating in sports.

In contrast, polycarbonate lenses are specifically designed to be impact-resistant and are widely used in safety glasses and eyewear for children. Plastic lenses, while lighter and safer than glass, can also fail to meet certain safety standards if they are not manufactured to specific impact requirements. High-index lenses are thinner and lighter but can be made from materials that meet or exceed safety standards. Thus, the risk associated with breakage makes glass lenses less favorable when considering safety in eyewear.