Why should you clean the eyeglass case?
Although the eyeglasses case is used less, it can not be separated from the glasses. If it is not cleaned for a long time, it will affect appearance and carry a lot of bacteria.
Does blue light cause damage to the eyes?
Businesses often associate blue light with mobile phones and computers that everyone frequently touches. There are also many terrible explanations about blue light on the Internet, ranging from causing damage to the eyes to causing cancer. Therefore, in recent years, mass media and academic circles have caused heated discussions about the possible impact of blue light on eye health.
It is believed that the reason why blue light harms the eyes is that blue light is not like ultraviolet light which is absorbed by the cornea and lens so that it cannot reach the retina. Blue light can reach the retina through the refractive medium of the eye, and over time it will cause the aging and functional degradation of the retina. But in fact, the eyes have many protection mechanisms in the process of evolution, such as squinting, pupil contraction, lutein contained in the macula of the retina, the anti-oxidant repair mechanism of the retina, etc., which can protect our eyes from the damage of blue light. Also, after scientific testing, the blue light emitted by electronic products is a few percent of the intensity of blue light in natural light, which means that as long as the electronic products are not used continuously every day (for example, more than 8 hours a day), blue light will not be causes obvious damage to the eyes.
Why does shape memory alloy have memory ability?
It starts with its microstructure. When a metal is solid, its atoms are always arranged in a regular way, forming a lattice. Under different conditions, such as temperature, metal may have a different structure, in which case it is said to be in a different phase. The change from one phase to another is called a phase transition. The properties of a metal change during a phase transition. The temperature at which a metal transforms is called the transition temperature. The difference between a shape memory alloy and other metals is that the phase transformation process in a shape memory alloy is reversible under certain conditions.
Types of Progressive Lenses
At the same time, there are different types of progressive lenses and they are standard PALs, short corridor PALs, computer PALs, and Reading PALs.
Standard PALs must fit your vision needs. They can be added to frames of your choice, but you need to ensure that the frames are the right width and height proportions to grant enough space for the gradient changes in the lens.
Short corridor PALs are made to fit into smaller frames so as to suit a wider range of eyewear styles.
Computer PALs are designed for computer users and other occupations that require strong intermediate and distance vision.
Reading PALs are designed for those who enjoy reading and they can opt for a pair of lenses with a larger close vision zone.
How can you tell if blue light glasses work?
It can be identified in the light. Ordinary lenses have a yellowish feeling under the reflection of light, while the anti-blue lens film color has blue on the yellow-green film, which is the cause of reflecting blue light out. Check the instruction manual to verify that the lenses contain radiation-resistant materials. When wearing, you can look at the electronic screen far away, and check if there is a sense of irritation to the eyes. The biggest difference between the regular lens and the anti-blue lens is the coating layer. If you look carefully, you can see that the anti-blue lens layer is very clear. Put the anti-blue light glasses on the fully open phone screen and observe if the covered area is blue. If it is, the prevention effect is good. This is because the blue light emitted by the phone is reflected on the phone screen by the lens.
Why do you need rimless glasses?
Traditional full-frame glasses can sometimes make your face look heavy, especially if the lenses are thicker. Rimless glasses can replace heavy frames without weight from the rims. This reduces the pressure on the nose pad, making your face feel lighter and more comfortable.
The birth of progressive lenses
In 1907, British optometrist Owen Aves first proposed the concept of progressive lenses and got the first patent of progressive lenses. In 1910, Henry Orford Gowlland designed and made a similar lens in Canada, but technical limitations prevented it from succeeding. In 1959, Bernard Maitenaz, a French optical and mechanical engineer, developed the first progressive lens, which was successfully put into the commercial market for the first time and became a milestone in the history of world optometry. With the development of science and technology, the design of progressive lenses has been greatly developed.
