What Are Progressive Lenses?
Traditional eyeglasses are usually single vision lenses with one prescription. Progressive lenses are multiple with three prescriptions in a pair of eyeglasses. Progressive lenses let you see comfortably at different distances, allowing you to see close, near, and far without changing your glasses. There are other kinds of multifocal lenses like bifocals and trifocals, but progressive lenses differ because of their smooth transition between prescriptions.
Bifocals and trifocals work similarly to progressive lenses and feature either two or three prescriptions in a pair of glasses. These lenses have definitive lines separating the prescriptions. However, progressive lenses don’t use these lines and allow you to easily transition between prescriptions.
Hence, in the following section, we will show you 6 different types of progressive lenses.
How much are rimless glasses?
Generally, the price of rimless glasses should be determined according to your choice of frame and lenses. Some of the rimless glasses are very expensive. Most of these rimless glasses are reserved for business people. Generally speaking, if it is for business people, the price will be more expensive. But if you just want to match some of the common glasses, rimless glasses' price usually will not be too expensive, about 15 dollars to 30 dollars. But business people's special glasses frame will be about 150 dollars to 350 dollars.
Evolution of hard coating technology
The first generation of the use of hard coating technology began in the early 1970s, the quartz material is deposited on the surface of a resin lens under vacuum conditions, form a very hard anti-wear film. However, due to the mismatch between the thermal expansion coefficient and the film base material, it is easy to delaminate and crack the film. Instead, it forms the mottle on the surface of the lens, and the effect is not optimal.
The second generation of hard coating technology is the use of the 1980s. The surface of the resin sheet is coated with a material with high hardness and not easy to be brittle and cracked by an immersion process. At this time, anti-reflection coating lenses had appeared and gained the recognition of consumers, but the mismatch between adding hard coating and anti-reflection coating still caused serious lens wear.
The third generation of hard coating technology was developed in the 1990s, mainly in order to solve the problem of wear resistance after coating resin lenses with an anti-reflection film. The hardened material evolved into a polymer organic matrix material.
Fourth-generation coating technology is dominated by silicon atoms, in which the hardened solution contains both organic substrates. It contains inorganic ultrafine particles, including silicon elements, which make the hard coating not only tough but also hard.
You need to buy real titanium frames.
In general, titanium frames range from hundreds of yuan to thousands of yuan. Many store counters display frames called pure titanium, but if you look closely at the labels, there is no indication of the titanium content or composition. When you buy titanium frames, check if they are titanium or pure titanium. In reality, pure titanium glasses frame refers to the composition of titanium more than 99%, so you can use the weight to see if it is pure titanium. If the frame is heavy, it is definitely not pure titanium.
The benefits of bifocal glasses
People with myopia often need to wear bifocal glasses after the appearance of presbyopia. The upper and lower parts of the lens have different diopters. The upper part is used to see distant objects, and the lower part is used to read and do close work. In addition to presbyopia, some people who work long hours in close quarters need bifocals to reduce eye strain. Studies have shown that long-term nearsightedness is the main cause of myopia. According to the adjustment principle of the eyeball and the height of the patient diopter, a reasonable measure is to wear myopia glasses with full correction when seeing the blackboard in class. When reading and writing. they should take off glasses or wear low myopia glasses. But the practice of continuously removing and putting on or changing glasses is clearly unrealistic. Bifocal glasses will solve this problem.
When do you need sunglasses?
The eye skin is more fragile than other parts. Long-time exposure to ultraviolet light will not only stimulate the eye to make it aging but may damage tissues like the cornea, leading to a series of eye diseases.? For more effective eye protection, sunglasses are a better choice.? Dazzling sunshine will make the eyes uncomfortable, affecting the clarity of the objects. Wearing sunglasses will greatly increase comfort.? When the sun is strong, when you go out, take the appropriate way to protect your eyes from the sun.? For example, wearing sunglasses can absorb ultraviolet and infrared rays, reducing sun damage to the eyes.?If you are driving in the direction of the sun, wearing sunglasses can not only protect your eyes from UV radiation but help the driver better observe the situation ahead, which is conducive to safe driving.
Acetate cellulose pellets are extruded by an injection molding machine, which is called an injection frame. Its characteristic is that it saves raw materials, can be mass-produced, has a lower cost, and is cheaper than a plate rack. But the firmness is not as good as the plate frame. However, injection frames are mostly used for glasses for the elderly and children because of their lightweight and resistance to allergies. The injection frame is made of laminated plastic. It is made by pasting a thin layer of plastic of one color on another thicker layer of plastic. Thick materials are mostly transparent pigments. It is also made of three or more layers of plastic.