When purchasing sunglasses, we must observe the outer packaging of the sunglasses, because there is a certain UV protection label under the outer packaging, which is expressed in English letters. When purchasing, everyone should check the outer packaging to see if there is a UV letter representation. If there is a letter representation, it indicates that sunglasses have UV protection functions, If there is no UV logo, then sunglasses do not have UV protection, so everyone should pay attention when purchasing them.

 

When purchasing sunglasses, you can take them in your hand and move them back and forth against a fixed object. If we find that the fixed object in front of us is getting larger or smaller when we move, we can determine that these sunglasses generally have a myopia function. If our eyes do not have a degree, then it is best not to purchase them, If you buy sunglasses like this, wearing them for a long time can cause certain damage to our eyesight. If you find any discomfort on your back when trying on sunglasses, you don't need to buy them, because this first sensation is very important and can play a decisive role in protecting our body in the future.

 

The optical center refers to the center position of the thinnest lens, which is also the position marked with the degree of myopia lens. Without the optical center, the thickness and degree of the lens will change accordingly. Therefore, if we wear glasses without wearing the optical center position of the lens through the pupil, it is theoretically impossible to accurately wear the prescription degree;