What is the best lens material?
Early lenses were made of natural materials because they were easy to get. But natural materials have obvious drawbacks. According to records of the Qing Dynasty, Emperor Yongzheng wore crystal glasses given by the imperial court, which greatly improved the efficiency of reading documents. However, because of the cold nature, the crystal will make the temperature around the eyes low when wearing, and part of the crystal lens has color so that the light into the eyes becomes soft.
Reading Glasses
At present, there are two prescriptions for reading glasses. One is to adjust the power of glasses with clear objects at close range, plus 1/3 of the power for adjustment. The other is to use low power that can see close objects clearly. The practice of many elderly people has proved that the latter one is better between two methods.
Do Blue Light Glasses Work?
When wearing blue light glasses, you may ask whether the blue light glasses really work. In fact, many users have the same troubles. To answer this question, some researchers have made research and have found that blue light glasses make it possible to remain fully engaged in our technologically advanced world, without taking on the negative effects of blue light.
With the blue light blocking glasses, you can focus on the task at hand without negative effects. Besides, with the blue light blocking glasses, you can even sleep well and reduce eye strain. You can also test your blue light glasses are real.
Cheap frames can cause skin irritation.
Some cheap frames may look like more expensive frames. But more often than not, they are made of low-level materials that can cause skin irritation over time. Cheap plastic frames can be bleached by ultraviolet light, leaving the surface rough after months of wear and tear. Cheap metal frames often contain nickel alloy, which can cause skin irritation.
Shorter lens beam
When you choose a glasses frame for kids, you must pay attention to that the lens beam must be short. The size of the lens beam stipulated by the national standard is 13~22mm. As a child, it should be controlled under 18mm. Otherwise, the position stability of the glasses will be poor.
Finally, they can not casually wear other people's glasses. The strength of each person's glasses, the distance between the optical centers of the two lenses, the length of the temple are different. So they can not casually wear other people's glasses.
The arm length is an important part of the size of the glasses.
Spectacle frames are standard optical products. Just like people's clothes and shoes, they all have their own size. Usually, specs for the size of the glasses are on the inside of the temple, on the bridge of the nose, or on the label. In general, the frames of the glasses are marked with the width of the frames, the width of the bridge of the nose, and the length of the arm. For example, the inner side of the temple is labeled: 52口 18-135, indicating the lens width of 52mm, the width of the nose bridge of 18mm, and the arm length is 135mm.
Single Vision Lens
Single vision is the most commonly used prescription lens. This lens type has a single field of view or a prescription ability of the entire lens and can be used to correct myopia (nearsightedness) or hyperopia (supervision). Some people need glasses to keep their distance and read. Instead of having a pair of single-vision glasses for each pair of glasses, bifocal or progressive glasses may be a more convenient choice. Unlike single vision, bifocal and progressive lenses are multifocal lenses with multiple focal points, such as distance and near distance. People whose prescription for spectacles list the numbers in the 'ADD' section require bifocals, progressive glasses, or reading glasses because your glasses need to add ADDitional to the distance prescription to see close distances.
