The Fashion Item in the Summer - Sunglasses
Sunglasses are one of the essential protective equipment in summer, both adults and children need a pair of sunglasses in summer. Sunglasses are the armor of the eyes to defend against UV rays which can not only cause damage to skin and hair, but also to our eyes!
Why should I Buy Sunglasses?
In addition to looking good and preventing sun glare, the more important role of sunglasses is to avoid being sunburned. Sun protection can prevent the skin of the eyes from photoaging and growing fine lines. If you don't protect your eyes from the sun, it can lead to cataracts, eye cancer and many other eye diseases.
Factors that Affect the Effectiveness of Sunglasses UV Protection
1. UV protection of the lens
The main reference is UV value. Sunglasses that are more than UV400 can block more than 99% of the ultraviolet light. Another is the lens color, lens color is actually not directly related to the performance of UV protection. So you can match and choose according to your skin tone and clothing color.
2. Size and fit of the lens
The larger the lens area and the better the fit with your cheeks, the better the UV protection. Wrap-around sunglasses have the best UV protection, while retro round glasses that are more decorative than practical - especially the ones that are so flat that they have almost no curvature at all - naturally have less protection.
Did You Choose the Right Color for Your Sunglasses?
The different colors of sunglasses block different levels of visible light, not UV. So it is possible that you buy black sunglasses that do not protect you from the sun and still end up with a very dark tan. Recommended colors in order of practicality: black (gray) > green > brown.
These three colors can be chosen at random on it in daily life. But if you drive with eyeglasses, please do not choose the green one which may be with color cast. Yellow is more suitable for outdoor activities. Most of the blue and purple sunglasses are used as decoration, not with sun protection function.
Are Black Sunglasses Better for Sun Protection?
Not necessarily. In fact, since sunglasses color affects only the amount of visible light transmission, choosing darker sunglasses will result in a darker field of vision. Our pupils adjust their opening size according to the darkness of our field of vision. Therefore, wearing darker sunglasses is likely to cause more damage to the eyes. The darker the field of vision, the pupil will be relatively open larger. If such sunglasses do not provide good UV protection, there will be more UV rays fall on the retina, the damage will be greater.
Do Ordinary Glasses Have UV Protection?
They are effective, but they are not a substitute for sunglasses. However, considering that the lens area of myopic glasses is generally not large, it is also unlikely to do a good job of covering, so there is still a gap between ordinary glasses and sunglasses, and they are not a substitute for sunglasses.
Common Sunglasses Lenses
1. Transitions
Transitions are the lenses that can automatically darken to help block some of the visible light when strong UV rays are detected. The principle is to embed photochromic molecules in the lenses, so that when the lenses are exposed to UV light, the shape and structure of the photochromic molecules change, blocking or absorbing a large portion of visible light and darkening the field of view. It can be restored to a transparent state when strong UV conditions are removed.
It is still very convenient for daily use. However, according to the principle of transitions, when the car windows are affixed with anti-UV film, transitions are no different from ordinary glasses, and can not play a role in reducing the field of vision brightness, anti-glare and so on.
2. Mirrored lenses
There are also some lenses that are like mirrors. In fact, the outer layer of glasses with a layer of reflective optical coating can reduce the total amount of light transmission of 10%-60%. The visibility of mirrored lenses is a little lower than the general sunglasses, so it is suitable for use in sand, water, snow and other sports activities.
3. Polarized sunglasses
Polarized lenses are used to prevent glare but not for UV protection. Sunlight is actually composed of many light propagating in different directions, and polarized lenses are used to filter out all the light except for those propagating in a specific direction. Polarized lenses filter light from various directions into one direction, thus reducing the irritation of bright light sources to the eyes - that is, anti-glare.
