Views: 54 Author: Site Editor Publish Time: 2020-09-03 Origin: Site
In fact, although we all cherish our eyes very much, many people around us have put on their glasses. The popularity of computers and mobile phones has seriously damaged everyone's eyesight. For middle-aged and elderly people, bifocal reading glasses, progressive reading glasses, professional bifocal reading glasses, etc. are their first choice for reading glasses.
So how to choose the one that suits you best? We can explain to you these two terms, bifocal and progressive lenses.
A bifocal lens is a lens with two focal points. Originally invented by Benjamin Franklin. At that time, the glasses he was wearing had only one focus, and switching between near and far would cause eye fatigue. Later, he divided the lens into two, and the two lenses with different focal lengths were combined to form a new lens. The first half is suitable for looking far, and the second half is suitable for looking close. Due to the imaging principle of the lens, even a half lens can still present a complete image without interference between the two images. Previously, both myopic glasses and reading glasses were called monofocal lenses, with only one focal point. Later developed into a bifocal lens, the same lens is divided into upper and lower parts. Use the upper part of the lens when looking far, and look down when you are close. It happens to be our reading distance. Naturally, the lower part is used.
Disadvantages of using traditional bifocal lenses: there is no area suitable for intermediate vision; visible lines in the middle of the lens; when changing from a short distance to a long distance focal length, a significant jump. People who use multifocal lenses for the first time may experience temporary dizziness, because a slight image jump occurs when you switch from the close-up part of the lens to the far-sighted part. Once the wearer has adapted to their new glasses, the problem usually resolves on its own.
Once you are used to wearing them, the bifocal lens is very convenient. Instead of having to carry two pairs of glasses, one for reading or working at close range and the other for far vision while driving, you only need to carry a pair of prescription glasses with you. The wearer of bifocal glasses either sees a distant object at the top of the lens, or looks down at the bottom of the glasses while reading a magazine or working on a computer.
It is a multi-focal lens, which is different from traditional reading glasses and bifocal reading glasses. Progressive lenses do not have the fatigue of eye focal length adjustment when using double-focal-length lenses. There is no obvious dividing line between the two focal lengths. It is comfortable to wear and has a more beautiful appearance, which has gradually become the best choice for presbyopes.
Disadvantages of using traditional bifocal lenses: there is no area suitable for intermediate vision; visible lines in the middle of the lens; when changing from a short distance to a long distance focal length, there is a significant jump. People who use multifocal lenses for the first time may experience temporary dizziness, because a slight image jump occurs when you switch from the close-up part of the lens to the far-sighted part. Once the wearer has adapted to their new glasses, the problem usually resolves on its own.
The advantage of progressive glasses is that it can solve your three vision problems, and you don't have to use different glasses at once to meet different vision requirements. These progressive glasses are definitely more advanced than bifocal or trifocal glasses. With progressive glasses, you will have a special lens that has more power and can provide a clearer field of vision for near, medium, and far vision, so only a pair of glasses can solve your vision problems.
We can choose the right lens according to our actual needs. Bifocal lenses and progressive lenses are used not only for reading glasses but also for sunglasses. Bifocal polarized sunglasses and bifocal sports sunglasses are very popular with consumers.