When choosing their sunglasses, pilots should always look for neutral lens tints (your ZEISS ophthalmic optician will be happy to advise you on the wide range of options). ZEISS Skylet® sun protection lenses are especially designed for applications where increased UV and glare protection and high-contrast vision are important. In this case, "high contrast" means being able to differentiate better between colours, so that a green meadow far in the distance is clearly – and unmistakably – perceived as green. This also enables pilots to "read" weather conditions better, especially cloud changes. As such, any impairment of the pilot's ability to recognise colours is largely eliminated so that all the instruments can be read perfectly and reliably – as with the ZEISS Skylet® "fun" and "road" variants.
Many tinted sunglasses or spectacles with prescription lenses, which mainly filter the blue portion of the light spectrum, impair this colour perception. This is why authorities such as the German Federal Aviation Offices clearly advise against such lenses. However, for those who still value a little colour, the new ZEISS gradient lenses offer a safe variant specifically suited for use within aircrafts. For example, the top section of the lens can be tinted dark brown and the bottom section a lighter colour that makes it easier to read the cockpit instruments. Spectacle lenses with optimum light reduction, a neutral colour pallet and 100% UV protection, match the strict lens requirements set for professional pilots by the authorities and pilots' associations.
By the way: pilots should avoid self-tinting or photochromic lenses. Self-tinting sunglasses always need a few seconds to adjust to changes in light and UV conditions.