Sunglasses of knowledge
Sunglasses also called shading mirror. The summer and plateau area, people often wear sunglasses, from the stimulation of strong light, block uv damage to the eyes. With the improvement of living standard, people more care of your eyes. In the sunlight, ultraviolet radiation damage to the eyes. Reaching the earth's surface ultraviolet rays of the sun's rays in the content is about 7%. The human eye cornea and crystal is vulnerable to uv damage the eye tissues. Cataract is relation with uv to close an eye disease, sunlight keratitis, corneal endothelial injury, eye macular change color, eye diseases such as retinitis were associated with ultraviolet light. Qualified sunglasses have the function of the interceptor ultraviolet and infrared light. Therefore, to say the summer wear sunglasses is one of the effective methods to protect the eyes from uv damage.
sunglasses generally divided into two major categories of light and dark, is made up of many colors. Evaluating the quality of the sunglasses, the emphasis should be the inspection focus and prism degrees, transmittance characteristics, surface quality and internal fault, assembly accuracy and several technical indexes such as cosmetic requirements.
a pair of good quality sunglasses can have the effect of shading and decorative appearance. But, in the market situation is not optimistic. Some vendors cynical, taking advantage of the consumers don't know much about the quality of sunglasses, the use of inferior materials, cheap Windows or other inferior materials of glasses. The material uniformity is poor, containing impurities such as stripe, bubble, can't keep out ultraviolet ray, does not conform to the human physiological requirements. What's more, using visible light transmittance is extremely low, but high uv transmittance of inferior plastic sunglasses, cause harm to consumers.
how to choose and wear sunglasses? The expert warns customer, must not only pay attention to the design of sunglasses, more attention should be paid to its inherent quality. Qualified sunglasses, wavelength at 315 nm to 380 nm long wave ultraviolet transmittance shall not exceed 10%, at 280 nm to 315 nm wavelength uvb rays transmittance should be zero. Wearing sunglasses, so as to make the eyes of the cornea, crystal and retina from damaging ultraviolet rays. Some cheap sunglasses not only can not filter out ultraviolet ray, it will hide because the visible light, after the ultraviolet irradiation is more significant, this kind of inferior than don't wear sunglasses.
sunglasses belong to light series. According to the regulations of the national standard, sunglasses only allows more with diopter of plus or minus 8 degrees, more than the error range is not qualified products. According to scientific research personnel of sunglasses on the market testing, nearly thirty percent of sunglasses diopter over tolerance, some even as high as more than 20 degrees. Experts point out that normal sight consumers put on the sunglasses, like wearing a pair of myopia or hyperopia mirror, after a summer, consumers will be inferior sunglasses & # 8220; Training & # 8221; In patients with nearsightedness or farsightedness. When you wear sunglasses appear the symptom such as dizziness, nausea, distracting, should immediately stop wearing.
experts noted that not all sunglasses can do the driver with a mirror. Many sunglasses on the market does not have the ability to identify different color traffic lights.