Young Brunette Girl With Sunglasses Reveals On The Field

• Blue or purple lenses are mainly cosmetic.
With the introduction of office computing, ergonomists may recommend mildly tinted glasses for use by display operators, in order to increase contrast.
Clear lenses are typically used to protect the eyes from impact, debris, dust, or chemicals. Some sunglasses with interchangeable lens have wet lenses to protect the eyes during low light or early morning activities.
While some blue blocking sunglasses are produced as regular sunglasses for exposure to bright sunlight, others—especially for macular degeneration patients—do not block light or other colors in order to function well in regular daylight and even dim sunlight. The latter allow the passage of enough light so normal evening activities can continue, while blocking the light that prevents production of the hormone melatonin. Low-blue tinted glasses are sometimes recommended to treat insomnia; they are worn in artificial lighting after dark, to reestablish the circadian rhythm.