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 advantages of metal frames
Its advantage is that the lens is fixed firmly, not easy to fall off. But the weight of the glasses increased slightly compared to the other frames. Full-frame glasses give people a sense of calm. The frame can cover the thickness of the lens very well, suitable for people with high degrees.
KoalaEye - Glasses For Men
Koala Eye glasses’ texture is very good. It looks good even for people in the workplace. The style of some frames has a very retro sense of luxury, which can stand the test of the fashion public. Besides, the professional degree is very strong. In recent years, retro is back in vogue. The texture brought by the pattern of some glasses is much better than other colors.
What Are Varifocal Glasses?
Varifocal glasses, also known as varifocals, varifocal lens, PLA, or progressive lenses, have a gradual change in strength from the top of the lens to the bottom with multiple focal points in between. Unlike bifocals, varifocal glasses have no specific area of lens strength, but progressive lens zones.
The way to look through varifocal glasses depends on what you want to look at. If you are looking at the distance, you look through the top of the lens. If you want to look at the close objects, you may need to move your eyes lower to keep the objects in focus. For the best close-up focus, you need to look through the bottom of the lens.
The benefits of varifocal glasses are that they do not need to buy or prepare 2 separate pairs of glasses or need to switch between frames for different vision needs.
However, if you wear the varifocal glasses for the first time, you may come across some problems.
What are progressive lenses?
Progressive lenses, also called progressive multifocal lenses, are lenses that have multiple focal points. If it is divided from the focal point, the lenses can be divided into single focal lenses, bifocal lenses, and multifocal lenses. The original intention of progressive multifocal lenses is to provide natural, convenient, and comfortable correction methods for presbyopia patients. A pair of glasses can see far away, close up, and mid-range objects. After wearing them, one pair of glasses is equivalent to using multiple glasses. Because of the different nature, characteristics and applicability, progressive lenses are more expensive than single vision lenses.
Eyeglasses chain stores have unified standards.
Due to the different management systems, the traditional business mainly relies on differentiated management and it enables member enterprises to have different business scope and modes and form complimentary benefits. Often, member enterprises are not required to implement unified management, with the unclear division of labor and uncertain responsibilities. The main store of a chain store and other stores shall form a clear division of labor in their professional functions, requiring the implementation of a unified management system, unified purchase, unified operation, and unified management. All the stores under the jurisdiction implement the unified management norm form formulated by the headquarters to form a unified norm.
Why are eyeglass frames are so expensive?
Plastic frames are often used for rimless glasses, but they are not very resistant to corrosion and break easily. The plate is a new type of plastic, and it is light and has high hardness, not easy to deform, but the surface is easily corroded by sweat. TR90 has features of wear resistance, good chemical resistance, solvent resistance, weather resistance, not burning, high-temperature resistance. Plastic steel does not contain any metal, but it is a kind of high-strength molecular material, lighter than TR90. They have a higher level in corrosion resistance and strength and other aspects. The frames made of good materials are more comfortable, durable, and textured in daily wear, and will not cause skin allergies. Plate, titanium, TR90, alloy are the most used materials on the market at present. The price is in dozens of yuan to hundreds, thousands of yuan.
