Many people deem that eyeglasses are exclusive to those who have vision problems, but actually there are numerous common people wearing glasses with plain lenses for decorations. We call these glasses plain eyeglasses or non prescription glasses.
Non prescription glasses have the functions of preventing wind and sand as well as protecting the eyes from the UV rays or infrared ray. What’s more, they can be used for decorations. Therefore, they are popular among the ordinary people who love beauty. Generally speaking, wearing non prescription eyeglasses is harmless to our eyes as they have no degrees. But poor-quality non prescription eyeglasses may still do harm to our eyes.
In theory, there are no degrees at all parts of the lenses of the non prescription glasses. However, for some inferior lenses, they are plain in the centers but there are still some degrees at the peripheral parts. As for whether these degrees are harmful or not, it depends on whether the error is within the reasonable range. According to the international conventions and state standards, the allowable vertex power error of the plain glasses shall be within±12 degrees, which has no effect on the vision of the wearer. But if the deviation is too great, the wearer’s vision will be damaged. For instance, the sunglasses available on the market are supposed to be with plain lenses, but as some inferior-quality sunglasses are with degrees the wearers will feel dizzy, headachy or swollen in the eyes, etc. after wearing them for a while. What’s worse, their vision may be deteriorated if they wear them for a long time.
For this reason, quality is also a very important factor that we should concern when we select non prescription glasses. If we feel dizzy or giddy or have other uncomfortable feelings when we are wearing a pair of plain glasses, just take it off immediately and don’t let it damage our vision.
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