It should be remembered that the main function of sunglasses is protective and secondarily decorative. Points are divided into categories according to the degree of transmittance of UV-radiation, which is abbreviated as UV. This information should be indicated on the label. To check UV protection, you will have to contact the optician where there is a special device.
Other criteria of protection - the degree of light transmittance lens. The first category of image-points, though they protect from UV rays, but from the blinding sun will not save. The second category of glasses perfect for everyday wear in the summer in the middle zone, if not too bright sun. The third category has a high degree of protection and suitable for beach holiday and travel in the mountains, in a tropical country. The fourth category is a darkened version, the third, for driving it is prohibited. It is believed that it should not be too often wear dark glasses to avoid eye strain, although there are all individually.
To ensure eyes safety glasses should fully absorb ultraviolet light. This is important because in dark glasses, the pupils dilate and eyes are not use of the inherent mechanism of protection against UV radiation. In the end, from these points it results in more harm than good.
High-quality sunglasses should provide comfort to the eyes in bright sunlight to avoid blinding. The image must be clear, to preserve their contrast and color distortion. The market today, you can find glasses with different additional coatings: anti-reflective, photochromic, hardened, waterproof, etc. as possible, choose more expensive eyeglasses, because they are usually better quality.
According to ophthalmologists, sunglasses with colored lenses harmful to the eyesight and mental state, so it is only suitable for photo shoots. Among the glasses which do not distort color perception of the surrounding space, gray, brownish, green, yellow. The latter is more suitable for cloudy weather. The light-reflecting mirror glass to well protect your eyes in the mountains and the sea.
In the manufacture of eyeglass lenses use different materials. This plastic with acrylic coating and nylon, and polycarbonate, and photochrom. The latter is a material-chameleon in the room, it becomes transparent, and the sun darkens. A good material for lenses is considered a mineral glass because it provides good protection and at the same time does not distort visual perception. Popular optical polymer CR-39. Lenses from it contain a UV absorber to prevent the development of eye diseases related to the sun. They are durable, light and not prone to scratches.
The choice of points of a certain material depends on the conditions in which you intend to wear them. If it is active, driving a motorcycle or car, do not buy glasses because if they crash, that may injure the eyes. You should not wear them and children. For active pastime, it is better to choose high-quality plastic sunglasses. When choosing plastic glasses, pay attention to the labeling. For example, marking UV400 reports about absorption of all types of ultraviolet radiation, UV95% absorption lenses 95% of UV rays. Generally, branded products are labeled and on the label and on the inner side of the ring on all the lenses.
Choosing the form of points, based on the shape of your face. Girls with round face suitable rectangular frame, with a square - rounded in the lower part of the form and bezobidnaya frame. Triangular face suitable glasses symmetrical rounded shape. If you have a long oval face, it will adjust a wide rim. And when choosing the color of frames, you can focus on the color of hair.