When we think about the choice of sunglasses, it is good to bear in mind the conditions in which we will use these glasses. Each condition has a different intensity of sunlight, as well as different types of lenses with a given light transmission. This light transmittance is given as the amount of light, expressed as a percentage, that it is able to penetrate the lens. The higher the percentage, the more light the lens passes through and the other way around. The lens with a transmittance of over 90% is therefore suitable for worse lighting conditions such as cloudy, overcast or snowy. On the contrary, we choose a lens with a lower percentage of transmittance for conditions where we have to protect our eyes even more from the sunbeams.
| CATEGORY | VISIBLE LIGHT TRANSMISSION (VLT) | USAGE |
|---|---|---|
| Cat 0 | 80 – 100 % | Indoor and cloudy weather |
| Cat 1 | 43 – 80 % | Low brightness |
| Cat 2 | 18 – 43 % | Medium brightness |
| Cat 3 | 8 – 18 % | Bright light, water & snow |
| Cat 4 | 3 – 8 % | Extreme bright light (glacier or desert) |