u003cbru003eA unique pop culture phenomenon, flapper style, was born in the United States in the 1920s. Women have cut fashionable short hair and wore short, loose and gorgeous skirts, which are all the rage. Due to the popularity of short hair styling, the comb market collapsed, and the women's accessories company run by American Sam Foster faced such a threat at the time. At this time, he discovered that the injection molding technique used to make combs can be used to make
sunglasses. So in 1929, sun
glasses made of celluloid were mass-produced for the first time and sold on the beach in Great West Side, New Jersey. Since then,
sunglasses have entered the mass consumer crowd. Today,
sunglasses are not only a weapon for UV protection, but also a must-have fashion item for street photography and concave modeling! Recommended reading: Attention! These people are not suitable for wearing sunglasses. When choosing and wearing sunglasses, there are always various doubts. For example: Why do you feel dizzy while wearing sunglasses? How to choose the lens color? ……What do the categories 1, 2, 3 and 4 on the sunglasses tag mean? First of all, we have to understand a word: transmittance. Transmittance, also known as transmission coefficient, refers to the ratio of the luminous flux through the lens to the incident luminous flux. Simply put, it is the transmittance or transmittance of visible light. For example, if the transmittance of a certain kind of sunglasses lens is 40%, that is, only 40% of the visible light can pass through the lens and enter the eye. According to the transmittance of visible light, lenses can be divided into 1-4 categories from light to dark: First category: light-colored sunglasses; the projection ratio is 43%~80%, the color is the lightest, the sunshade and the reduction of luminous flux are the least, and it is generally used as a fashion accessory mirror The second category: light-colored sun-shading mirror; the transmittance is 18%~43%, and the color is slightly lighter, and it is used when it is cloudy or cloudy; the third category: sun-shading mirror; the transmittance is 8%-18%. Most sunglasses belong to this level and are suitable for outdoor activities such as seaside and mountaineering; four categories: special purpose sunglasses; transmittance of 3% to 8% is used more in skiing, desert, electric welding and other environments. According to requirements, the transmission ratio of driving mirrors should be greater than 8%, so category 4 sunglasses cannot be worn when driving. Some sunglasses can cause the wearer to be unable to identify the traffic signal or difficult to identify, leading to traffic accidents, because the traffic signal transmittance of these sunglasses is unqualified. Sunglasses should have no degree. Why do you feel dizzy when wearing some sunglasses? 1. Lens color: Wearing sunglasses with dark lenses (too low visible light transmittance) in daily environments (such as indoors) for a long time can cause visual fatigue and severe symptoms such as dizziness and nausea. 2. frames: For example, the temples are worn too tightly, oppressing the temples, causing dizziness, or the discomfort of wearing the stipules of the glasses, 3. Lens processing problems: lenses have no luminosity (except for myopic sunglasses) ), but if the size of the lens during processing is too large and forced to squeeze into the frame, under the stress of such long-term distortion of the lens, the optical index of the lens will therefore exceed the standard. Wearing such lenses can cause dizziness from light to light, and can affect vision in severe cases. In addition to the above, it is not ruled out that some people feel uncomfortable with progressively dyed sunglasses lenses. Are there any taboos in wearing sunglasses? Glaucoma patients: After wearing sunglasses, the visible light entering the eye decreases, and the pupils will naturally enlarge. This change in pupils has no effect on healthy people, but for glaucoma patients, it increases the obstruction of the aqueous circulation in the eye, which can easily induce acute attacks of glaucoma, such as red jelly, eye pain, headache, nausea, vomiting, sharp decline in vision, etc. symptom. Therefore, it is not recommended to wear sunglasses for glaucoma patients or those with suspected glaucoma. Colorblind patients: Wearing sunglasses for people with full colorblindness does not have much effect. However, some color-blind patients lack the ability to distinguish only a few colors, and they are even more unable to distinguish colors when they wear sunglasses. There are also people with night blindness, optic nerve omentitis and other people who are not suitable for wearing sunglasses. In addition, do not wear sunglasses indoors. Because sunglasses will make people's eyes in a relatively dark light, then the pupils will subconsciously dilate, and vision will be affected. In order to see more clearly, it is natural to watch the object vigorously. Over time, over-adjustment of the eyes may cause symptoms such as visual fatigue and photophobia. Related Reading: Brand Sunglasses, Fashion Sunglasses
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