Biscuits, drinks and other foods, since they rot, usually have a shelf life, want to know the shelf life, see food packaging bags.
But, if ask you, usually wear glasses and sunglasses have a shelf life?
Estimated that many people could not answer.
These two years, a message appeared on the net, say you wear sunglasses at ordinary times, the shelf life of only two years, two years have to change a new pair.
The news make many people don't calm: I wear sunglasses for three or four years!
Sunglasses factory ms YC9702 sunglasses black/C3 lens dazzle colour blue everyone wear glasses for three or four years is very common, two days ago, citizens to Ms. Wang in WeChat see a message 'sunglasses also have shelf life, use for a long time is easy damaged corneas', this news let her sit still.
Four years ago, Ms. Wang from abroad spent 2000 yuan to buy a pair of sunglasses, is usually referred to in the sunglasses.
Because in study abroad before, local uv strong, so she bought a pair of good quality sunglasses, hope and durable.
Compared to other things, sunglasses of utilization rate is not high, only in the summer or sunlight intense wear, although already bought four years, but the actual use of time add up to only about half a year or so.
'But tell me, this article sunglasses have to be in two years, it also has a shelf life, if you are using will cause all sorts of problems, including corneal damage and other eye diseases.
'Ms. Wang said, this let her worry, also hesitant: change the glasses, this pair of glasses with good, a little loathe to give up;
Don't change it, again afraid influence eye health.
In addition to wear sunglasses, Ms. Wang at ordinary times or nearsightedness, is respectively equipped with a pair of myopic glasses and recessive myopia glasses, don't wear sunglasses, she also need to wear myopia glasses.
Learned that sunglasses may have a shelf life after, she also query the expiration of the myopia glasses, it was found that there are many articles to tell her, glasses and has a shelf life.
Ms. Wang also find out the packing for sunglasses and myopic lens, she found the match myopic lens, no product manuals, and sunglasses on foreign language instruction, does not use fixed number of year or shelf life.
Reporter then randomly interviewed side a few citizens, whether myopia glasses or sunglasses, find your glasses wearing length is widespread in more than two years.
Myopia glasses and sunglasses is there a warranty on September 4, the reporter interviewed several optical shops to city streets, also consulted by taobao several flagship brand sunglasses, are also differ.
A Shanghai glasses company Tmall flagship store customer service 'cuckoo', says she hasn't heard sunglasses and 'two years warranty' say, the correct understanding of it should be: anything with long time, use effect may be at a discount, the same is true of sunglasses.
City jiangbei a store manager Mr Zhang, according to the customers to the store usually glasses, also won't consulting the expiration of the glasses, in fact, when the glasses are rarely consider the shelf life of the problem.
But they will advise customers according to usage, regular replacement lenses.
'The reason is very simple, with glasses knows, use glasses at ordinary times is need maintenance, especially to wipe dust, will wear lenses, and general use for two years or so, the lens also can appear scratches, etc. , if used for three or four years, will be more outstanding, is also the time to change the lens.
'Everyday use of myopia glasses, for example, the current market popular is the resin lenses, in daily use of the lens is wiped, will cause the lens natural wear and scratches.
Wear lenses can cause 'wide Angle scattering phenomenon of light -
Fog degree ', namely the light no longer even through the lens, Dai Jingzhe depending on the vision is easy to feel not clear.
In fact, after lens wear many consumers don't know, but the eyes to know.
Eyes on its own to adjust that Dai Jingzhe see, the longer it will increase the fatigue of the eye, resulting in reduced vision.
Ray-ban RB4221 -
F men sunglasses 6170/55 blue shelf life but it is difficult to define glasses have the best life in addition, the reporter also to the eye doctor, glasses chain and so on has carried on the consultation, to the expiration of the glasses, and didn't get an authority.
Although the glasses without the authority of the shelf life, but for glasses best use fixed number of year, but there is a consistent point of view.
Many experts inclined to think that myopia glasses best use cycle for 1 ~ 2 years, more than two years later, can appear the phenomenon such as lens scratched, easy to produce visual fatigue, dry eyes, dry eyes, such as conditions, can also lead to myopia aggravating.
, according to the official Xinhua News Agency reported recently released by the university of Sao Paulo, Brazil, unveiled a new study, the researchers suggest, change a pair of sunglasses best for two years, because the lens for a long time to accept the sun insolates, will reduce the uv protection ability, easy to damage the cornea, causing vision problems.
Researchers in Europe, Australia, New Zealand and South America to do simulation experiment, the sunglasses under the sun simulator, 30 cm distance markers, 'sun' 50 hours continuously, the degradation degree of lens uv protection ability.
The study found that sunglasses to wear or security for two years.
Sunshine is different in different areas of the world, tropical countries and the area of the highest uv, even in the winter is also high, means that the sunglasses uv protection function degradation is faster in these places.
In addition, the residents in southern hemisphere sunglasses it frequently than people in the northern hemisphere.
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