The lenses of prescription glasses
Common materials for lenses include glass, resin, and PC. The glass is fragile and heavy, and few people wear it anymore. PC film is tough and not fragile, but it is not resistant to high temperature and the surface is easily scratched. The most common type of lens on the market today is the resin lens, which is light in weight, hard to break, and reasonable in price. At present, it is generally recommended that you choose resin sheets, and it is recommended that people with ultra-high myopia choose glass sheets.
Generally, lenses can be divided into spherical and aspherical surfaces according to different curvature designs. When choosing, refer to the degree of the eye. For people with lower degrees, There are fewer differences between the two shapes. For people with moderate to high myopia, aspherical lenses will have better imaging effects and clearer vision.
When choosing a lens, a parameter that is often mentioned is the refractive index. Common refractive indexes are 1.56, 1.60, 1.67, and 1.74. With the same degree, the higher the refractive index, the thinner the lens.
How To Choose Better Night Driving Glasses?
Choose and buy glasses to use a special night with anti - strong night driving lens. The demand is to block 80-90% of the strong lights and harmful lights, and at the same time to make the road more clearly. Choose glasses with thicker lenses, they are more durable and protect the eyes of drivers against irritation and accidental breakage. As common sunglasses and color-changing glasses are only suitable for daytime wear, wearing them at night will seriously affect the driver's vision.
Common light yellow night driving glasses can only block a small amount of light, and is not very suitable for night driving glasses standards. Therefore, in the choice of lenses of night driving glasses, we must do the selection and demonstration of the national authority of the formal institutions to test products, to achieve the desired effect in actual use. Don't buy products that are not up to standards from vendors. Such products not only do not block the lights but may affect the driver to see the road ahead, affecting the safety of the train operation.
Choose clear glasses for kids to keep safe.
Safety is very important no matter in what aspect, glasses are no exception. Especially for children, they are more active. The lens is best made of PC, and the frame is best made of materials with high toughness, such as TR90. Service fixed number of years of this kind of picture frame is long.
How to Choose Reading Glasses?
If you need reading glasses when using a computer, you may want to choose a lower reading glasses power. This is because most people view their screen from a greater distance from their eyes than when they are reading a book or a magazine.
However, if you need reading glasses for looking at something very close or very small, you may need a pair of stronger power glasses.
In most cases, when two reading glasses’ powers seem equally suitable, choose the glasses with the lower power. Picking reading glasses that are too string typically will cause more discomfort problems than reading glasses that are a little too weak.
What are the causes of lens damage?
When the force area of the lens is small, the impact resistance of the lens is worse. When subjected to the impact of external forces, the lens will naturally be squeezed and cause breakage.
In particular, some lenses with low degrees and high refractive index are possible to cause this phenomenon. When the frame fell from a height due to wrong placement, there is a collision between the edge of the lens and the ground or hard objects. It will produce a broken or collapsed edge. In the process of the lens falling from high, the impact force is larger, and the stress point is smaller. When the glasses are falling, the upper edge of the lens, the convex groove of the upper frame, squeezes against the lens. The middle part of the upper half is easy to cause edge collapse. In the process of processing the template, the template is not accurate, so that the glasses side and the frame can not be uniform fusion, and the force of the lens is uneven. It will be easy to lead to greater stress in some parts, resulting in edge collapse.
How to protect rimless glasses?
With the continuous improvement of people's living standards, many people begin to pay attention to their quality of life. In the past, many people thought that wearing glasses was for correcting eyesight glasses, but now more and more people use them for decoration, and rimless glasses meet the needs of consumers. Because of its light structure, giving people a sense of fashion, so it is loved by many business people. So how do you protect your rimless glasses?
A Suitable Nose Pad
The Nose pad must fit the nose to the maximum extent possible. If they do not fit, the opticians have special pointed tools. It's best not to adjust the nose pad yourself. A lot of store staff are afraid to adjust the nose pad, just because it is difficult. The general store processing master will adjust the nose pad. The nose pad can be adjusted on the premise of the same rake angle.
