Nowadays sunglasses come in all colours and shapes. However we have to consider that all lenses don’t provide the same protection.
Lens tints are not indicative of the level of protection that a lens provides. Category rating number is just a classification that refers to level of lens tint intensity, how dark it is and situations in which it’s more suitable to use one category or another.
Category Absorption Characteristics Use
0 0 to 20% None or very light tint. Days with weak level of sunlight, cloudy weather.
1 20 to 57% Light tint. Days with average levels of sunlight. Not suitable for night driving.
2 57 to 82% Medium tint. Days with sunny weather in autumn, winter and beginning of spring. Not suitable for night driving.
3 82 to 92% Dark tint. Very sunny days, outdoor activities – the most usual coating. Not suitable for night driving.
4 92 to 97% Very dark tint. Snow, heights over 3.000 metres. Not suitable for drivers and road users.
It’s essential to highlight that a higher category rating number doesn’t necessarily mean that a lens that offers more eye protection. It simply means they are darker lenses because they’ve engineered for strong sunlight conditions. The level of protection of a certain lens depends on whether that lens blocks UV radiation and also on the quality of manufacturing materials.
Any colour, but always with UV protection
Dark sunglasses without protection against UV radiation are especially dangerous. These shades only cope with sunlight, but they can’t block UV radiation. So the pupil dilates (because a smaller amount of light enters through it) and even more UV radiation strikes the retina, increasing damaging effects.
Other aspects to consider
We also have to take into account that glasses specially designed for specific activities offer more protection and greater comfort, not only because of their lenses’ category rating number but also because their shape and manufacturing materials have been carefully selected to endure certain conditions of use. At Optical H, you will find the sunglasses you need narrowing down search results according sport or physical activity:
