In the previous article, we discussed “Best Polarized Sunglasses For Men“. In this article, let’s talk about “How often do you need to change sunglasses?”.
Various foods such as biscuits and beverages usually have a shelf life because they will rot and deteriorate. If you want to know the shelf life, just look at the food packaging bag. So, is there any service life for the glasses and sunglasses that I usually wear? Some people will say that the sunglasses you usually wear have a service life of only two years, and you have to replace them with a new pair in two years. This news shocked many people because their sunglasses have been worn for three or four years! So, do sunglasses really have a service life? How long does the span life of sunglasses?
The protective effect of sunglasses on eyes
Ultraviolet rays have an effect on the skin, as well as the eyes. The strong sunlight at noon not only dazzles the eyes, but the ultraviolet rays in the sunlight can damage the eyes. When ultraviolet light passes through the lens in the eyeball, it is absorbed by crystal proteins, causing the destruction of crystal cells and free radicals. Over time, the lens will become cloudy and cataracts will appear. Ultraviolet rays can also cause damage to the retina, macula, etc. This is the cause of age-related macular degeneration in many elderly people. In short, it is important to wear sunglasses to protect your eyes!
The span life of sunglasses
Everyone has different opinions on this issue. Some people think that the correct understanding of the use period of sunglasses should be that if anything is used for a long time, the use effect may be compromised. The same is true for sunglasses.
Usually, customers go to the optical shop to match glasses, and they do not inquire about the expiration date of the glasses. In fact, the issue of shelf life is rarely considered when matching glasses. However, the clerk will advise customers to change the lenses regularly according to their usage. The reason is simple. Everyone who wears glasses knows that normal use of glasses requires maintenance, especially wiping dust, which will wear the lens. Generally, after two years of use, the lens will be scratched. If you use it after three or four years, the situation will become more prominent, and it is time to change the lenses.
Take the daily use of myopia glasses as an example. At present, resin lenses are popular in the market. Wiping the lenses in daily use will cause natural wear and scratches of the lenses. The wear of the lens will cause the "wide-angle light scattering phenomenon-haze", that is, the light will no longer pass through the lens uniformly, and the wearer will easily feel that the vision is unclear when looking at the object. In fact, many consumers do not know after the lens is worn, but the eyes know. Eyes rely on their own adjustment to make the wearer see clearly. If things go on like this, it will increase eye fatigue and cause vision loss.
The optimum life of sunglasses
In addition, consulting with ophthalmologists, there is not an authoritative statement about the shelf life of sunglasses. Although there is no authoritative definition of the service life of sunglasses, there is a relatively consistent view on the best service life of sunglasses. Many experts tend to believe that the best use period for myopia glasses is 1 to 2 years. After more than two years, the lens will be scratched, which is prone to visual fatigue, dry eyes, and astringent eyes. It may also lead to aggravation of myopia.
Recently, the University of Sao Paulo in Brazil has released a new study. Researchers suggest that it is best to replace a pair of sunglasses in two years, because long-term exposure to sunlight will reduce the ability to protect against ultraviolet rays, which is easy to damage cornea, causing vision problems.
Researchers conducted simulation experiments in Europe, Australia, New Zealand, and South America. They placed the sunglasses under a solar simulator at a distance of 30 cm from the luminous point and continued to "expose" for 50 hours to see the degradation of the lens' UV protection ability. Studies have found that it is safe to wear sunglasses for two years. Different regions of the world have different sunlight. Tropical countries and regions have the highest levels of ultraviolet rays, even in winter, which means that the UV protection function of sunglasses degrades faster in these places. In addition, residents in the southern hemisphere change their sunglasses more frequently than those in the northern hemisphere.
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