Lens a category applies to all tint colours, grey is the most popular. Grey doesn’t distort colour and black is the biggest selling frame colour and let’s face it, it looks really cool. But there is a science to lens tints and it’s important to have an understanding of what it all means. When you buy a pair of sunglasses they come with the percentage of light transmission already selected. When you are having custom made prescription lenses you have the choice. You can select from Cat 0 to Cat 4, you may think Cat 4 is the best when actually it is completely unadvisable to use for driving for example.
So in the real world let’s take a look at each lens category and how it might be used in the world of sport. The 5 categories’ 0 to 4 refers to a band of light transmit ion, the percentage of light that passes through the lens.
Shades of grey:
Visible Light Transmission (VLT) – This is the measure of how much light your sunglass lens lets through to your eye and can be expressed as a percentage, therefore a VLT of 1% means very dark glasses indeed, and a VLT of 100% means all the light is getting through and the lens is, therefore, a 'clear lens'.
Rather than quote a percentage for each lens they are categorised as follows:
- Category 0; 80-100% VLT
- Category 1; 46-79% VLT
- Category 2; 18-45% VLT
- Category 3; 8-17% VLT
- Category 4; 3-8% VLT