How Often Should Women Change Their Sunglasses
1、 How often should women change their sunglasses
The sun protection ability of women's sunglasses has been decreasing year by year, and it is recommended to replace them every 2-3 years.
The basic material of women's sunglasses lenses can absorb some ultraviolet light, and the coating of sunglasses lenses can also reflect some ultraviolet light. Many women's sunglasses lenses also add UV absorbing materials to their lenses. In this way, the vast majority of ultraviolet rays can be 'shut out' and no longer harm our eyes. But this protection is not permanent.
Because ultraviolet radiation carries high energy, it can cause the material of sunglasses to age, reducing the ability of sunscreen ingredients to absorb ultraviolet radiation. The shiny coating on the outside of sunglasses is actually the result of metal vapor deposition, and these coatings may wear out, oxidize, and reduce their reflective ability. All of these will compromise the UV protection of women's sunglasses.
Professor Liliane Ventura and her team from the University of S ? o Paulo in Brazil conducted a study: in Brazil, wearing sunglasses for 2 hours a day resulted in a decrease in their UV protection ability after two years and they should be replaced.
Considering the sun exposure situation in China, experts suggest that sunglasses should be replaced every 2-3 years depending on the frequency of use.
2、 What will happen if women's sunglasses are not changed for a long time
1. Lens wear and tear
There are currently three main types of lenses: resin polarizing film, resin PC lens (AC, CR39, nylon are temporarily classified under this category), and glass lens. Resin polarizers and resin PC lenses that are lightweight and comfortable to wear are not wear-resistant and will wear out over time. In fact, many people do not know about the wear and tear of lenses, but their eyes know. The eyes rely on self-regulation to make the wearer see clearly, which over time can increase eye fatigue and lead to a decline in vision. So pay attention to placing the lenses facing upwards in daily life to avoid wear and scratches on the mirror surface.
2. Lens aging
Long term exposure of lenses to sunlight can reduce their UV protection ability, easily causing damage to the cornea and leading to vision problems. Researchers conducted a simulation experiment by placing sunglasses under a sunlight simulator, 30 centimeters away from the light emitting point, and continuously exposing them to sunlight for 50 hours to observe the degree of degradation of the lenses' UV protection ability. Research has found that the UV protection ability of lenses may degrade. The sunshine varies in different regions of the world, with tropical countries and regions having the highest levels of ultraviolet radiation, even in winter, which means that the UV protection function of sunglasses deteriorates faster in these areas. Although the lens materials of high-quality women's sunglasses are all special materials, they will also age over time. If the UV protection function of sunglasses decreases, it can damage the cornea and retina, leading to diseases such as solar keratitis and corneal endothelial damage.
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