How to Tell If Your Progressive Lenses Are Correct?
Progressive lenses are popular among people who are over 40 and they can be used to correct presbyopia. If you have a pair of progressive lenses, how can you tell if the progressive lenses are correct or not? If you do not know, you come to the right place. This post will show you how to tell if your progressive lenses are correct.
How do I know If I have progressive lenses? There are two parts of the lens you can check. The first is how the lens sits in front of your eyes. If you are not able to see in the distance, either centration is way off the lenses are too high or the lens power is not correct. However, when checking the lens sitting in front of your eyes, you should be able to maintain a natural posture in your neck and see sharp when reading or while focusing on the distance. If you raise your chin high while reading or hold it low to see in the distance, it is not correct.
How do you identify the refractive index of lens?
In reality, this problem is often a problem for optical shop practitioners, sometimes they worry about whether the manufacturer's lenses match the nominal value of the refractive index. We need a prop, and that's the camber. Because it can be used to measure the strength of the lens. The luminosity of the lens can be calculated by subtracting the curvature of the inner and outer surfaces of the lens. The curvature difference of a lens of the same luminosity is inversely proportional to the refractive index, that is, a lens with a higher refractive index only needs a smaller curvature difference to achieve the same luminosity.
Color process of Contact lenses
Pigment printing process
It refers to the direct printing of pigments or patterns on the inside of the lens and then drying, which is the main production process of poor-quality chromatic contact lenses. Usually, small factories and small workshops use this method. The lens is being phased out because the pigment can easily seep out from the surface during wearing, causing discoloration and staining, and irritation to the eyes, which is a big risk.
Pigment build-in process
To be specific, the lens made by sandwich technology is a three-layer structure, the front and rear are colorless transparent layers, and the middle is a colored layer. After the processing of sandwich technology, the color layer is wrapped in the middle of the front and rear transparent layer, so that the pigment will not contact the eyes, which will not cause irritation and injury to the eyes. The downside of this process, however, is that the lenses are slightly thicker than normal contact lenses and are less oxygen-permeable, so they are not suitable for long-term wear.
The pressed film manufacturing process
This is a relatively new method of a similar sandwich process, and the color (pattern) is also made between the front and rear layers of the lens. But the color (pattern) is used to fill in the film process. During lens curing, the pigment seeps into the material instead of sticking to the surface. It feels as if the lens is covered in color within a single layer. This reduces the middle layer and makes the lens thinner, which naturally makes it more comfortable and permeable to oxygen.
Clear non-prescription sunglasses are a trend.
Clear glasses will not appear old, as long as the choice of their own frame is good-looking, although it is often said that a round face is suitable for angular frames, and a three-dimensional face is more suitable for rounded frames, but the collocation of face shape and frame can not be generalized. A transparent picture frame gives a person a feeling of intellectual, restoring ancient ways of literature and art model. There are a lot of people who use it to reflect their modeling. It seems that there is a pure sense of feeling. And people who use it do not lose the taste of literature and art, and there is a unique personality. Half of the transparent glasses are made of TR material and plate, which is light and comfortable to wear and have many styles.
Be careful to choose driving sunglasses.
Many people take it for granted that the darker the color, the better its UV protection. The function of filter the ultraviolet ray of the sunglasses is concerned with the film of plating only. Especially for long-distance drivers, wearing sunglasses that are too dark can make eyes more tired. And entering dark areas such as tunnels from the strong sun is more dangerous.
Some drivers are slightly myopic, but when they wear sunglasses, there's a problem: their eyes are more likely to tire and the vision can deteriorate, just like driving at night. So, if the slightly myopic drivers want to wear sunglasses, they must be equipped with a myopic degree of the lens.
Thick black frame
During that time, in the memory of every nearsighted person, there is such a pair of black frame glasses. They can be big can be small, and can be square, round. If you wear this kind of glasses, you are the most handsome boy in the whole street. Of course, black-rimmed glasses have their benefits. Many big-name fashion magazines often use them to give stars a concave look during the shoot.
How Should Glasses Fit?
Make sure your pupils align correctly. The combination of frame, arm, bridge, and lens measurement can affect the placement of your pupils within your lenses, which is essential to the proper function and comfort of your prescription. To ensure glasses fit properly, the pupils should align horizontally in the center of your lenses.
Also, you should consider your face shape. When choosing a pair of suitable glasses, you should consider what face shape you have.