The FDA requires that sunglasses meet certain requirements for lens transmittance, UV protection, and impact resistance. Lens transmittance refers to the amount of light that is allowed to pass through the lens, and the FDA sets limits on this to ensure that sunglasses do not interfere with vision. UV protection refers to the ability of the sunglasses to block harmful UV radiation, and the FDA requires that sunglasses block at least 99% of UVA and UVB radiation. Impact resistance refers to the ability of the sunglasses to withstand impacts without breaking or causing injury, and the FDA sets standards for this as well.
In addition to these requirements, the FDA also requires that sunglasses be labeled with information about their UV protection and lens transmittance. This helps consumers make informed decisions about the sunglasses they purchase.
Other countries have similar regulations for sunglasses to ensure that they meet certain standards for quality and safety.