How to Tell If Lenses Are Plastic or Glasses?
If you want to know if your glasses are made of glasses or plastic, the safest way is to ask the optician from whom you bought the glasses. If you do not want to ask the optician, there are several ways to differentiate them, such as sound, weight, and temperature.
Lightly tap the lens against your teeth or your ring. If the lens emits a high, ringing tone, it is a glasses. On the contrary, the plastic will have a low thud like sound when tapped.
Glass lenses are much heavier than plastic glasses and glass lenses feel colder to touch while plastic glasses feel warmer since it is a better insulator.
After learning what lenses you have, it is time to show how to remove coating from glasses.
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.
What are browline frames?
The name browline comes from the design of the frame. The upper part of the frame is thicker than the lower part so that the wearer's natural eyebrow line can be noticed. The top is usually made of acetate or plastic, and the bottom of the lens is wrapped with a thinner wireframe. Later, the browline frames have also been modified to meet the needs of more customers. Some browline frames use nylon wire instead of metal wire in the lower part, while the browline frames with metal wire are more durable and stable. If people with high myopia want to have a pair of half-rim glasses, browline frames are a good choice.
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.
Are yellow lenses good for night driving?
Yellow lenses are very effective even in low light conditions. They enhance contrast while you're driving. In other words, they broaden your horizons and allow you to see more cars, people, and objects on the road. Especially when you're driving at high speeds on dark roads, this widened, enhanced view can help you see more clearly. The transparent driver's glasses effect is not good. Headlight glare can be understood as dazzling light. The lens should be looked for from the angle of the stain. But the color should not be too dark to ensure safe driving at night. It is better to polarize the light. It can greatly improve the anti-glare effect.
Sunglasses
Sunglasses have a visible light transmittance of about 20% and can absorb ultraviolet and infrared rays well. It also has a variety of colors such as light green, light gray, light brown, etc., used to protect in different occasions. Among them, light gray lenses have little effect on color recognition. Light brown glasses make the blue sky look darker and reduce the transmission of green light. Light green lenses reduce the transmission of red light.
Sunglasses not only have a wide range of varieties, but with the improvement of decoration and health care effects, their scope of use has become more extensive. As the time to update sunglasses can be rapid, fashionable men and women would love to have multiple sunglasses to match clothes to satisfy their pursuit of fashion.
How Should Glasses Fit?
In order to enable the glasses to fit on your face and ears, you need to pick the right frame width for your face. The width of your frame is the entire horizontal measurement of the front of your frames. A correct frame width will ensure your eyes are properly aligned in the center of your lenses for optimal vision. The frame width should be slightly wider than your face but with the space between your temple and frame no larger than a finger’s width.
Moreover, you also should ensure the Arm Length is right for you. The arms of glasses should run along with your temple and wraps around your ears. The arms should run horizontally and sit comfortably around your ears only touching your head right before your ears. Of course, you can find the arms-length of glasses on the side of the temple.
