Types of Optical Frame Glasses
The full-frame glasses have good strength, suitable for athletes and children to wear because the lens is completely protected by the lens ring. They are suitable for a variety of refractive parameters of the lens. The upper part of the lens ring is made of metal or plastic materials. The lower half of the lens ring is made of a very fine nylon wire like the lower part of the lens ring. Rimless glasses are lighter than full-frame glasses. Rimless glasses can be divided into parts type and integral type. The part type consists of a nose bridge (together with the nose pad) and two temples. The combination glasses are divided into two parts. Usually, the front group is equipped with colored lenses, and the rear group is equipped with lenses for correcting refractive errors. The folding glasses can usually be folded at the bridge of the nose and the temple to reduce the space when stored or carried and are mostly used for making reading glasses.
How to choose rectangular glasses?
Look at the facial features in the aspect of proportion. If your features are delicate, which makes you look petite, you can choose some wider glasses so that you will increase your mental outlook, making your features prominent. On the other hand, if your features look solid and take up a large space of your face, go for narrower frames, because wider frames will make you look tired and add weight to your head.
How to buy prescription glasses online
Consumers should choose different styles of frames according to their age and professional characteristics. Because everyone has different face shapes, different interpupillary distances, and different diopters, the size of the frames should vary from person to person.
Lenses are divided into glass lens, resin lens, and PC lens, and you can choose according to your preferences. The glass lens has a stable refractive index, good abrasion resistance, and stable optical performance, but it is relatively heavy and easy to break. Resin lens with high light transmittance is light, safe, and not easy to break, but the surface is easy to wear. PC lens has a high refractive index, but the surface is easy to wear.
Why can't you wear expired contact lenses?
Contact lenses have a throwaway cycle. If the contact lens has been opened, the shelf life of the contact lens is calculated from the day it was opened. Contact lenses have a life cycle. The life cycle is the shelf life of contact lenses. For example, if you wear daily contact lenses, you will have to throw them away. If you wear monthly contact lenses, they will have a shelf life of one month. Even if you wear them only a few times, you will still have to throw them away. The shelf life of contact lenses is calculated from the day the lenses are taken apart, not from the number of days they have been worn.
After the shelf life of contact lenses, there will be some cases like lens aging, hardening, lens discoloration, decreased transparency, lens deformation, thickening, an increase of lens protein, and other precipitates. The microbe is easy to deposit, resulting in poor oxygen permeability. If you continue to wear it, it is easy to cause inflammation of the conjunctiva and corneal hypoxia, and the comfort level will be much worse. It is suggested to analyze the case according to your own care. Once the contact lenses have the above cases, they should be replaced in time.
Possible effects of driver's lens color on driving
Color plays a very important role in your everyday driving experience -- red, yellow, and green traffic lights, among many other signs and signals, are designed to grab your attention and keep you safe. If everything you see is yellow, you may make the wrong decision at the red light and may cause an accident. To keep your vision clear in night and day conditions, anti-glare night driving glasses are not just for night driving.
Common Bifocal Glasses Problems
In this section, we will list some common bifocal glasses problems.
First, it may take a couple of weeks to adjust the bifocal glasses. You may not get used to wearing your bifocal glasses overnight. When you wear the bifocal glasses for the first time, it may be difficult to adapt them.
However, knowing the correct part of the lens to look through is crucial to giving you the vision correction you need, whether it is distance or near vision, for different activities.
To adapt to the bifocal glasses, you had better wear them all day or as often as you can. If you don’t wear your new glasses enough, it can make the adaption period last even longer.
Besides the above bifocal problem, there are other problems with bifocal glasses. The second problem of bifocal glasses could be that the bifocal line is too high and you might lack adequate distance vision. So, the bifocal line could be obvious and it would not be beautiful. However, if you want a pair of glasses without a visible line, you could consider progressive lenses. You will feel older while wearing them, without having to worry about the line through the center of your glasses.
Design principle of aspheric lens
Early optical lenses use spherical lenses. Because the glasses were small round frames, the problem of lens edge aberration was not paid attention to. It wasn't until large frames became popular that the problem became apparent. For the spherical lenses, aberration cannot be corrected with the combined lens. Only a few variables of the lens can be found to reduce aberration and improve clarity. Aspheric lenses are designed to reduce the aberration of optical correction lenses and to make lenses flatter and reduce lens magnification. We can get clearer, thinner, lighter-quality lenses. Thus, aspheric lenses are used to reduce aberration and astigmatism to a minimum, close to the natural vision of the naked eye. The spherical aberration can be reduced by changing the curvature of the edge. The refraction in the central region is high and decreases evenly toward the edges.
