Dr. Wei Ruihua, an ophthalmologist, and Dr. Guo Junlai, who has rich experience in optometry and matching glasses, remind people that when buying sunglasses, they should first look at the anti ultraviolet and strong light blocking functions of the mirror, and then look at the style and price. The following six points should be noted:
1. Colored eyes mirrors are not equal to sunglasses, so recognize the UV protection sign
The ultraviolet wavelength is below 400 nm. When choosing sunglasses, you should recognize the “UV400” logo. This logo indicates that it can resist ultraviolet rays. Some sunglasses will be marked with “anti ultraviolet” or “100% anti ultraviolet”, which also indicates that they have anti ultraviolet function. Do not buy without such identification. There are many colored glasses in the market. Many people think that as long as the glasses have color and can block the sun, they are sunglasses. In fact, this is a misunderstanding. UV protection and strong light blocking are the two main functions of sunglasses. The color of the lens is mainly used to block strong light, so that people can see things without dazzling. Whether the lens can prevent UV is not related to the color, but mainly depends on the material and coating of the lens. If you only want to look beautiful or cheap, buying a pair of colored glasses without UV protection will do more harm than not wearing mirrors. Because the human body has a self-protection reaction, when the eyes encounter strong light, the pupil will naturally shrink, reducing the ultraviolet rays entering the eyes. However, if you wear colored glasses without UV protection function, the light intensity received by the eyes will weaken, and the pupil will enlarge, allowing ultraviolet rays to enter.
2. The lens color should be moderate.
If the color of the lens is too light, the strong light blocking function will be weakened, and you will still feel dazzling and uncomfortable when you move in a sunny place. The color of the lens is too dark, which will affect the visual object, even interfere with the natural color of the object, and make it difficult to distinguish traffic signals. Generally, sunglasses of medium depth color can meet the needs of people’s daily life.
3. The specific color of the lens should not affect the natural color of the object to ensure eye comfort
There are many colors of sunglasses lenses on the market, mainly including tea, gray and green, but also red and yellow. The reason why strong sunlight makes people uncomfortable to see is mainly related to the irritation of yellow light to eyes. Generally, the tan, gray and green lenses have strong resistance to yellow light. The specific color can be determined according to personal preference, but no matter what color lens is selected, it should be based on the principle that the color of things seen is not distorted, the traffic signal can be effectively identified, and the eyes feel comfortable.
4. The lens surface is smooth, without ripples, bubbles and abrasion marks, and the visual object is not deformed.
Sunglasses are flat lenses. There are strict standards for lens surface treatment, curvature and diopter, especially the diopter should be within 0.008. Only in this way can we see things without deformation. Otherwise, wearing sunglasses with excessive diopter will cause eye discomfort and dizziness. The simple way to judge the quality of the lens is to take the glasses and move them slowly up, down, left and right in front of your eyes. It is better to see whether the objects are deformed through the lens. It is better to look at the line shaped objects such as the window pane and door frame. If the lines are bent, it means that the diopter of the lens is unqualified and should not be purchased. In addition, pay attention to whether the surface of the lens is smooth and free of ripples, bubbles and abrasion marks.
5. Don’t make the frame too large.
At present, large frame sunglasses are very popular and popular among young people. However, the size and style of glasses should be determined according to the individual’s eyes and face. Generally, as long as the lens can cover the eyes and completely block the sun, there is no need to follow the fashion and choose Sunglasses with very large frames. Sunglasses are too large, and the wide and thick frame will compress the infraorbital branch of the trigeminal nerve. Generally, after wearing such glasses for 1 to 2 weeks, it will lead to eye soreness, numbness between the orbit or cheeks, and dullness of perception, which is harmful to eye health.
6. Crystal mirrors can’t protect against ultraviolet rays
The tawny crystal glasses sold in street stalls or shops are quite popular with some middle-aged and elderly friends. They think that wearing this kind of crystal glasses is very pleasing to the eye. In fact, crystal glasses do not have any UV protection function, and must not be used as sunglasses.