Have you noticed the "shelf life" of sunglasses?

Have you noticed the "shelf life" of sunglasses?

The hot summer has not yet passed, and the sun is "unscrupulous". Many people like to wear sunglasses when they go out for sun protection. However, have you noticed the "shelf life" of sunglasses? A new study shows that the "shelf life" of a pair of sunglasses is about 2 years.

After the "expiration date", the sunglasses are likely to lose their function of protecting the eyes.

The British media quoted researchers from the University of Sao Paulo in Brazil as saying that prolonged exposure of lenses to sunlight will   reduce their ability to protect against UV rays.

Exposure to sunlight may degrade your sunglasses, the lenses may become lighter and reduce their ability to resist drag, known as their   shatter resistance index, the study said.

The World Health Organization published the article "Ultraviolet Radiation and Human Health", which pointed out that 5% of the 18 million   people who go blind due to cataracts in the world every year are caused by ultraviolet radiation. Ultraviolet rays can also cause other serious   eye diseases - keratitis, retinal damage, cataracts, macular degeneration, snow blindness, etc. Therefore, sunglasses that can filter ultraviolet   rays have become an important equipment for us to protect our eyes in the sun.

The researchers conducted simulation experiments in Europe, Australia, New Zealand and South America. They put the sunglasses under a   solar simulator, 30 centimeters away from the luminous point, and continued to "exposure" for 50 hours, while observing the degree of   degradation of the lens' UV protection ability.

Experimental results show that due to the difference in sunlight in different regions of the world, the UV protection function of sunglasses will   degrade faster in tropical countries and regions with the highest UV levels.

Sunglasses degradation varied with latitude, with the tropical UV index being particularly high in summer and not decreasing in winter, the   study said.

Experimental results show that due to the difference in sunlight in different regions of the world, the UV protection function of sunglasses will   degrade faster in tropical countries and regions with the highest UV levels.

Sunglasses degradation varied with latitude, with the tropical UV index being particularly high in summer and not decreasing in winter, the   study said.