In the previous article, we discussed “Should I wear glasses all the time for myopia?”. In this article, let’s talk about “Which lens is used for myopia?”.
Regarding the treatment of myopia, one is to wear glasses for myopia, and the other is to perform professional corrective surgery. Many people don't know what material the lenses of myopia glasses are good and how to choose them. In fact, the first thing is to look at the refractive index. The higher the refractive index is better. Second, it is to look at the material of the spectacle lens. For example, glass materials, resin materials, and PC lenses have their own advantages and disadvantages. When buying, look at your needs.
Refractive index of spectacle lens
It is generally believed that the higher the refractive index, the better the spectacle lens. Such spectacle lenses are relatively thin, and of course, the price is a bit expensive. When the refractive index increases, the direction of the light entering the lens will change greatly, the focus will move to the lens, the focal length will be smaller, and the diopter will become larger. In order to keep the diopter unchanged, it is necessary to reduce the curvature of the lens, that is, to reduce the curvature of the mirror surface, so that the thickness of the lens can be reduced. This is why the larger the refractive index, the thinner the lens is. Under the same premise of other things, the larger the refractive index, the thinner the lens, the lighter and more beautiful the lens, and the higher the price, but the larger the refractive index is not the better.
The material of spectacle lens
It is not only based on the refractive index to select but also depends on the material of the spectacle lens. Then there are several types of materials for myopia glasses. For example, there are glass, resin, and better PC lenses. There are also obvious differences between the three materials. The use rate of glass lenses is not high now. The myopia lenses that you often see are mainly resin lenses. These resin lenses are more suitable for wearing. Also, you can choose PC lenses. There are many PC lenses on the market. This kind of lens is very light, high toughness, and not easy to break, so it is also very popular with everyone. These three materials have their own advantages and disadvantages, so decide which one to buy according to your needs.
The correct method for lens cleaning
Wet it with water first, and then add a little detergent or hand sanitizer to each lens. Dip your fingers to the back of the lens, and then scrub with your fingers. Be careful not to use too much force to prevent the lens from being worn out by grit.
The key here is to rinse. First of all, never use hot water, because hot water will cause the lens to expand due to heat, which will crack the film in the resin lens.
Finally, you should rinse with cold water, do not wipe with a cloth, because any glasses cloth or suede can not perfectly wipe the lens, even the more you wipe it, the more indistinct it gets. If there is hard dust in the cloth, it will scratch the lens.
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