As the weather gets colder, various fashionable sunglasses have begun to do promotion. These sunglasses can not only block the sun and protect against the sun but also help you look cool. Children's sunglasses have also become a must-have for many families. As for the price, sunglasses are also a mystery, ranging from tens of bucks to hundreds of dollars.
Are these cool-looking sunglasses effective? Can everyone wear sunglasses? How to choose sunglasses that suit you? What damage will buying poor sunglasses cause to your eyes?
Besides looking good, why do we wear sunglasses?
As we all know, people usually adjust the size of their pupils to adjust the light flux in the sun. When the light intensity exceeds the adjustment ability of the human pupil, it may cause visual fatigue and light damage to the human eye. Long-term ultraviolet radiation can also easily lead to eye diseases such as pterygium, palpebral fissures, cataracts, and macular degeneration.
Sunglasses can block uncomfortable strong light and protect the eyes from ultraviolet damage.
UV light is invisible light with a wavelength of 10nm to 400nm in sunlight. According to the wavelength, it can be divided into near-ultraviolet light (UVA), far ultraviolet light (UVB), and ultra-short ultraviolet light (UVC).
UV light in sunlight may harm the eyes. The degree of damage is related to the wavelength. The longer the wavelength of ultraviolet light, the greater the harm.
With the change in the earth's environment and the destruction of the ozone layer, in hot weather, the direct sunlight from the sun and the reflected ultraviolet rays from the ground and water are very high in illumination, which will cause cumulative damage to the conjunctiva, cornea, lens, vitreous body and retina of the eyes.
Therefore, it is very important to choose to wear sunglasses that can effectively block ultraviolet rays when doing outdoor activities or traveling, which can effectively block the damage of ultraviolet rays to the eyelid skin, cornea, conjunctiva, lens, vitreous body, and retina.
It is not true that the darker the color of sunglasses, the better.
For a long time, many people have such a misunderstanding that sunglasses are to resist strong light, so the darker the color, the better. In fact, it is not true.
The color depth of the lens only affects the visible light absorption performance and has nothing to do with the ability to block ultraviolet rays. Ultraviolet rays are invisible light. Preventing ultraviolet rays from entering the eyes does not depend on the depth of the lens color, but is determined by the ultraviolet absorber in the sunglass material. Even colorless optical lenses can absorb ultraviolet rays. Now most transparent optical resin lenses have very good ultraviolet protection capabilities.
Studies have shown that even if you wear regular sunglasses, some ultraviolet rays still enter the eyes, mainly from the reflection of the back surface of the lens. Therefore, in the past two years, optical lenses with ultraviolet protection on both the front and back surfaces of the lens have been available.
Too dark tint lenses are not only meaningless but also potentially harmful to the eyes. When the color is too dark, the eyes must dilate the pupil to maintain normal vision but harmful light also comes in. If you wear inferior sunglasses that cannot block ultraviolet rays, more ultraviolet rays will enter the eyes than when you don't wear sunglasses, which is more likely to cause eye damage. For drivers, sunglasses with too dark lens tints can delay the time that the eyes need to send images to the brain, slowing down the driver's reaction speed.
In the actual selection of lens colors, experts suggest that medium depth is better, such as gray, brown, and green. The principle of lens color selection includes that the color of the surrounding environment is not distorted after wearing it, the edges of objects are clear, and different colors of traffic lights can be effectively identified.
Different occasions and environments have different requirements for sunglasses.
When driving, the driver is in the car and keeps looking forward. At this time, in addition to the glare of the sun, there are also reflections from the road surface and the glass walls of buildings on both sides. Therefore, wearing sunglasses is also related to driving safety. When drivers choose sunglasses, polarized lenses are the first choice.
Let's talk about how to choose sunglasses, and who is suitable for wearing sunglasses and who is not suitable for wearing sunglasses.
The most important function of sunglasses is to filter ultraviolet rays, and how to determine whether sunglasses have this function is actually very simple. Check the label. Sunglasses with UVA, UVB, and CE logos, especially those with "UV400", can block all ultraviolet rays.
What harm will be caused to the eyes when wearing inferior sunglasses?
The most important problem of inferior sunglasses is that they cannot protect against ultraviolet rays.
Some of them have very dark-tinted lenses. After wearing them, the pupils in the dark will become larger, which will increase the light entering the eyes.
If the eyes are exposed to ultraviolet rays for a long time, it is easy to cause dry eyes, fatigue, and tears. In severe cases, it may cause irreversible damage to the conjunctiva, cornea, lens, and retina of the eyes, and it is easy to develop diseases such as palpebral fissures, pterygium, cataracts, and macular degeneration.
It is particularly important to remember that inferior children's sunglasses have no ultraviolet protection function and have a "diopter" that exceeds the standard allowance. Some are just toys, but they are sold as children's sunglasses.
Children's vision and visual function are in the development stage. If they often wear glasses of poor quality that do not meet optical requirements, it will increase the burden of eye adjustment and convergence, affect the normal development of visual function, and easily cause harm.
How to identify the quality of sunglasses?
At present, there are very clear requirements for the diopter, prism, UV protection factor, etc. of sunglasses.
Every pair of sunglasses with qualified quality needs to have an "ID card". Consumers can pay special attention when purchasing, and ID cards are more than just one.
Firstly, it includes the product inspection report, which will make detailed descriptions of professional data such as product appearance inspection, frame size, high-temperature stability, and UV protection factor.
Secondly, it includes the product tag certificate, which involves the product name, manufacturer, place of origin, UV protection factor, quality grade, product category, etc.
Thirdly, if it is an international brand, the seller also needs a brand authorization letter, customs declaration, etc.
Experts say that good sunglasses must meet four characteristics: comfort to wear, clear vision, safety and durability, and beautiful design. It is not necessary to choose the expensive ones. Select the right pair that suits you.
Baby should better wear sunglasses after 3 years old.
Nowadays, sunglasses are no longer just for adults. Many parents also buy them for their children. Some of them wear sunglasses to look cool when they are two or three years old. Celebrities often bring their babies wearing sunglasses in photo shoots to look cute and cool.
Should babies wear sunglasses? Yes, but consider it at least after the age of 3.
Doctors do not recommend that babies who are too young wear sunglasses. There is an important premise: young babies do not have many opportunities to be exposed to strong sunlight under normal circumstances, so there is no need to wear sunglasses.
In addition, wearing sunglasses may affect the visual development of babies. Before the age of 3, is considered to be a sensitive period for the development of a baby's vision. During this visual development process, the baby's eyes need to be constantly stimulated and exposed to clear images to better stimulate visual development. If you wear sunglasses frequently during this period, it may prevent the baby's eyes from receiving light stimulation, and then vision problems including amblyopia may occur.
After the age of 3, the baby's vision development is relatively complete, and the opportunity to go out and be exposed to the sun is gradually increasing, so it is also necessary to wear good quality sunglasses correctly at this time.
However, in summer, the ultraviolet rays are strongest between 12 noon and 2 pm, so parents are advised not to let their children go out for exercise during this time.
Do middle-aged and elderly people also need to wear sunglasses?
From the perspective of healthy eye protection, sunglasses are equally important for middle-aged and elderly people and help prevent the occurrence and development of eye diseases.
However, for the elderly, special attention should be paid to the wearing time. The time of wearing sunglasses should not be too long. It is recommended to take them off and rest every one or two hours. Especially for some elderly people with shallow anterior chambers of the eye structure and the risk of angle-closure glaucoma, it is not recommended to wear sunglasses.
There are also "contraindications" for wearing sunglasses. Some patients with eye diseases cannot wear sunglasses, such as glaucoma, color blindness, night blindness, etc.
