Winter has arrived, but the sun is still shining brightly. As everyone’s health awareness increases, more and more people are wearing sunglasses when going out. For many friends, the reasons for replacing sunglasses are mostly because they are broken, lost, or not fashionable enough… But in fact, there is another important reason that is often ignored by everyone, and that is that sunglasses “expire due to aging.”
Recently, we often see some articles reminding that “sunglasses have a lifespan of only two years and must be replaced after that time.” So, is the lifespan of sunglasses really only two years?
Sunglasses really “get old”
The basic material of the sunglasses lens itself can absorb some ultraviolet rays, and the coating of the sunglasses lenses can also reflect some of the ultraviolet rays. Many sunglasses lenses also have UV-absorbing materials added to them. In this way, most of the ultraviolet rays can be “kept out” and can no longer harm our eyes.
But this protection is not permanent.
Because ultraviolet rays carry high energy, they will age the materials of sunglasses and reduce the ability of sunscreen ingredients to absorb ultraviolet rays. The shiny coating on the outside of sunglasses is actually the result of metal vapor deposition, and these coatings may wear, oxidize, and reduce their reflective ability. These will reduce the UV protection ability of sunglasses.
In addition, if we do not take care of our sunglasses, it will often cause direct wear of the lenses, loosening of the temples, deformation, and damage of the frame and nose pads, etc., which will affect the normal use and protective effect of the sunglasses.
Is it really necessary to replace it every two years?
First of all, I want to state that this is not a rumor, but this research really exists.
Professor Liliane Ventura and her team from the University of Sao Paulo in Brazil have done a lot of research on sunglasses. In one of their papers, they did mention that they recommend changing sunglasses every two years. This conclusion has also been quoted by many media, and now we often see similar Chinese content.
But this conclusion actually has a premise, that is, the researchers calculated based on the working intensity of sunglasses in Brazil…that is, if you wear sunglasses for 2 hours a day, the UV protection ability of the sunglasses will decrease after two years. , should be replaced.
Let’s feel it. In Brazil, the sunshine is like this in most places… After all, it is a passionate South American country, and more than half of the country is in the tropics…
So from this perspective, people in northern my country are unlikely to be able to wear sunglasses for 2 hours a day. Therefore, we can save some money. Depending on the frequency of wearing it, it is no problem to wear it for one or two more years and then change it. The recommendations given by some well-known sunglasses or sports sunglasses manufacturers mostly depend on the frequency of use, and they should be replaced every 2 to 3 years.
This will make your sunglasses last longer
A pair of qualified sunglasses is often not cheap. If we take good care of it, it can protect us longer. Specifically, we only need to:
- Store it in time when not in use to avoid wear or direct sunlight.
- Friends who are driving, please do not leave your sunglasses on the center console to expose them to the sun.
- When placing sunglasses temporarily, remember to point the lenses upward to avoid wear.
- Use a glasses case or pouch, as these specialized storage containers have a soft interior that won’t damage your lenses.
- Don’t just put your sunglasses in your pocket, or throw them into your backpack and rub them against other keys, wallets, cell phones, etc., as this can easily damage the coating of the glasses. It may also directly crush the frame.
- When cleaning sunglasses, you can use detergent, hand soap and other detergents to make foam to clean the lenses. After rinsing, use a lens cleaning cloth to dry it, or directly use special wet lens paper. Compared with “dry wiping”, this is more convenient. Not prone to scratches.
- Wear your sunglasses correctly and do not place them high above your head, as they can be easily knocked off or broken, and the temples may be broken.
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Just keep these in mind when choosing sunglasses
In fact, it is not difficult at all to choose qualified sunglasses. You only need to look for the sunglasses with the “UV400″ or “UV100%” logo in a regular store. These two logos indicate that the sunglasses can achieve nearly 100% protection against ultraviolet rays. It is enough to have a protective effect.
How to choose the color? Generally speaking, for daily use, we can give priority to brown and gray lenses, because they have less impact on the color of objects, are more convenient for daily use, especially driving, and will not affect the driver’s observation of traffic lights. In addition, friends who drive can also choose sunglasses with polarized lenses to reduce glare and drive comfortably.
When choosing sunglasses, there is one aspect that is easily overlooked, and that is “shape.” It is easy to think that sunglasses with a larger area and a curvature that fits the face shape have the best sun protection effect.
If the size of sunglasses is not appropriate, the curvature does not fit our face shape, or the lenses are too small, even if the lenses have adequate UV protection, they will still easily leak light everywhere, greatly reducing the sun protection effect.
We often see articles saying that using a banknote detector lamp + banknotes can determine whether sunglasses are reliable or not. Because sunglasses can protect against ultraviolet rays, the money detector lamp cannot illuminate the anti-counterfeiting mark through the sunglasses.
This statement is actually open to question because it is related to the power and wavelength of the money detector lamp. Many currency detector lamps have very low power and fixed wavelengths. Some ordinary glasses can block the ultraviolet rays emitted by the banknote detector lamps, preventing the banknote anti-counterfeiting marks from lighting up. Therefore, it is safer to use professional instruments to judge the protective ability of sunglasses. For us ordinary consumers, it is most important to look for “UV400″ and “UV100%”.
Finally, to summarize, sunglasses do have the term “expiration and deterioration”, but we don’t need to replace them every two years.
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Post time: Oct-09-2023