Choosing sunglasses for sun protection, look for those models in which the lenses are closest to the eyes, but not touch eyelashes. In these glasses you will have less to worry side light.
There are five levels of protection points from light effect: transparent, light, medium, strong, and maximum. As a rule, manufacturers say the figure in the product certificate. Cheap glasses the degree of protection indicated on the sticker placed over the lens. There you can find a note about UV protection. To verify the accuracy of information on special equipment by an ophthalmologist.
Manufacturers produce glasses with different types of lenses as absorbing radiation, and reflecting it. Well-tinted Windows filter visible light, but ultraviolet waves protect the weak. In the sale easy to find glasses with black, brown, yellow, green, blue and pink lenses — it all depends on the fashion season and the imagination of the designer. However, when purchasing such a accessory you must consider that the yellow and brown glasses although protect from bright light better than others, but distorts color, so not suitable for driving. The eye safe lenses are gray or gray-green.
Tinted lenses can be useful in bright light, but indoors will be a hindrance. Universal solution are the photochromic glasses, known at home as "chameleons". Their lenses are made with the addition of special substances to darken under intense lighting, so they are able to change the transparency depending on the external conditions.
Polarized lenses — the best solution for athletes and drivers. Through technology, developed in 1937, they protect from direct sunlight, without reducing the depth of colour and detail. The famous manufacturer of polarized sunglasses — Polaroid — also produces a tinted model. So before buying you must ensure that you choose the suitable glasses. To do this, look through them for any LCD and tilt your head 45 ° to left or right. If the image blacks out completely, lenses are truly made according to the technology of polarization.
In addition to toning and polarization of lenses is frequently used in mirror coating. Thanks to a thin layer of reflective lenses produce less heat, and better protect the eyes from part of the spectrum. On the other hand, the coating easily damaged, the lenses are covered with scratch and are long.