A good pair of dark lens glasses should meet Australian Standards. The Standard AS/NZS 1067:2016 requires sunglasses and fashion glasses to meet performance requirements for providing protection and glare reduction.
There are four categories:
0 No UV protection
1 Low level of UV protection
2 Medium level of UV protection
3 High level of UV protection
4 Very high level of UV protection
You will find that most fashion glasses are not classified by the Australian Standard, which usually means they don’t provide any protection. Or they are in category 0 or 1 – and don’t provide adequate protection from UV rays.
To get maximum protection for your eyes, look at choosing sunglasses that have a category 2, 3 lens.
Category 2 and 3 sunglasses provide medium and high protection against sun glare, while category 4 sunglasses have very dark lenses that are created to use in extreme exposure situations, like mountain climbing in the snow.