Choose clear glasses with the right size for kids.
The choice of children's glasses should be based on the size of the child's face and the height of the nose. Most of the bridge of your child's nose is low, so you can choose an adjustable eyewear frame with a separate nose pad to avoid touching your eyelashes or wearing the glasses uncomfortably. If the frame is too small, the field of view will become smaller. The frame is too large, they are not stable, and the weight will increase. So children with glasses frame should be moderate in size.
Evolution of hard coating technology
The first generation of the use of hard coating technology began in the early 1970s, the quartz material is deposited on the surface of a resin lens under vacuum conditions, form a very hard anti-wear film. However, due to the mismatch between the thermal expansion coefficient and the film base material, it is easy to delaminate and crack the film. Instead, it forms the mottle on the surface of the lens, and the effect is not optimal.
The second generation of hard coating technology is the use of the 1980s. The surface of the resin sheet is coated with a material with high hardness and not easy to be brittle and cracked by an immersion process. At this time, anti-reflection coating lenses had appeared and gained the recognition of consumers, but the mismatch between adding hard coating and anti-reflection coating still caused serious lens wear.
The third generation of hard coating technology was developed in the 1990s, mainly in order to solve the problem of wear resistance after coating resin lenses with an anti-reflection film. The hardened material evolved into a polymer organic matrix material.
Fourth-generation coating technology is dominated by silicon atoms, in which the hardened solution contains both organic substrates. It contains inorganic ultrafine particles, including silicon elements, which make the hard coating not only tough but also hard.
Method of wearing the contact lens
Wash your hands before putting on contact lenses, and be careful not to leave long nails, to avoid contamination of the lens by bacteria and nail scratches. Place the contact lens on the tip of your index finger, face-up, and pull your upper and lower eyelids apart with the middle fingers of both hands. Look straight ahead and place the lens gently into the eye (attached to the cornea). Remove the index finger and look down so that the lens is attached to the cornea, and slowly relax the eyelids with the middle fingers of both hands. Blink gently several times (or roll your eyes) to remove bubbles.
The main parts of glasses
1. Spectacle lenses
One of the most important accessories for glasses is spectacle lenses. Due to the increase in myopia patients, the demand for spectacle lenses is also very large, but the prices of spectacles on the market are also uneven. To know whether the spectacle lens is good or not, you can't just look at the price of the product, but learn more about the value of the lens itself. For example, the resin lens is lighter and suitable for patients who wear it for a long time. The quality of the optical glass lens is better, and it is not easy to break, suitable for some elderly people.
The quality of spectacle lenses is also a key consideration. The market generally classifies lenses based on their structure, materials, and usefulness. The information on spectacle lenses is mostly chemical substances. It is very beneficial for us to select some good-quality lens materials. It is not only necessary to consider the function of the lens, but also to consider whether the lens material is harmful to the human body. Generally, the crystal stone materials are very safe and reliable, and we can choose carefully.
2. Spectacle frame
Another important figure in eyeglasses accessories is the frame. For those who like lightweight glasses, it is more appropriate to choose ultra-light frames or half frames. However, the frame must have durable and play a good role in maintaining the lens, otherwise, it will lose the meaning of the frame. Of course, the temples are also a part of the frame. There are also nose pads for glasses accessories. Many people have more requirements for nose pads. Generally, they choose soft ones that are not easy to press on the bridge of the nose.
The anti-reflection principle of the anti-reflection film
Anti-reflection Coating, known as anti-reflection membrane, is called anti-reflection coating in English, or AR membrane for short. The basis of anti-reflection is the wave and interference of light. The principle is: Two light waves with the same amplitude and the same wavelength are superimposed, then the light wave amplitude is enhanced. The two wavelengths and amplitudes are the same, but the superposition of wavelengths with different wave paths (similar to dislocation) cancels each other out. Therefore, the anti-reflection film plated on the surface of the lens uses this principle to make the reflected light generated by the front and rear surfaces of the film layer interfere with each other, thus canceling each other and achieving the effect of reducing reflection.
How do myopic glasses work?
The formation principle of myopia is that when the light from the outside world enters the eyeball, it is refracted by the eyeball's refractive system and cannot be accurately imprinted on the retina. The image is in front of the retina. If a concave lens is placed in front of the eye before the light enters the eye, it shifts the focus of the myopic eye from a point in front of the retina to the back, so that it lands directly on the surface of the retina. When parallel light passes through a concave lens, it diverges, meaning that it has already diverged once before entering the eye and then is refracted normally by the eye's refractive system. When the light is refracted through the eyeball, the distance of the image will be longer. So the distance of the image will be correspondingly pushed back compared to the non-divergent light. But it will just fall on the retina, and the image will be accurate in the right place.
Eyewear stores are close to consumers.
Location is a very critical factor. A reason why customers can walk into your store is that if it is convenient to go to your store. If there are two stores of the same size, your store is in front of the school gate and the other one is 500 meters away from the school, then your store will definitely attract more customers than the one 500 meters away.
