Why are rimless glasses so expensive?
Although the overall volume of materials selected for rimless glasses is a little less, the special structure of rimless glasses requires much higher physical properties (flexibility, surface texture, etc.) and processing accuracy than TR, PEI, and other materials. Rimless glasses require higher quality lenses. For example, lens materials with a refractive index of 1.56 tend to be brittle for rimless glasses and should be chosen with caution. Generally speaking, the time of processing about three pairs of half-frame glasses is equal to the time of processing of a pair of rimless glasses.
What is blue light?
To prevent blue light, we must first understand what blue light is. The visible light with a wavelength range of 400-500 nanometers is called blue light. The light sources used in daily LED lighting and display products, including mobile phones, flat panels, and TVs, are mostly LED light sources excited by blue light. However, not all blue light is harmful to the human body. The human eye has an extremely low tolerance to blue light radiation in the 400-440 nanometer range. When the light intensity enters this threshold, photochemical damage is likely to occur. However, blue light radiation in the range of 459-490 nanometers is essential for regulating the human body's circadian rhythm and can affect the secretion of human melatonin, which in turn has an impact on the body's biological clock, alertness, and mood.
Scientifically effective anti-blue light lenses must not only block harmful blue light but also cannot filter beneficial blue light. Most of the ineffective anti-blue light products on the market currently have two types of problems. One is that there is almost no protective effect on the blue light in the vulnerable zone of the human eye. The other is excessive protection, shielding the blue light spectrum in the beneficial band so that the blue light that is beneficial for physiological adjustment cannot enter the human eye. At the same time, the color of the lens is yellow, which is prone to color shift, aggravating visual fatigue, and even inducing the risk of myopia.
Tortoiseshell frame glasses can be said to break connotation completely, and this is a very stylish and slightly exaggerated style. It is recommended that fair-skinned, trendy hairstyle and stylish clothes should be worn by boys. After all, if you want to wear stylish tortoiseshell frame glasses, you need clothes and hairstyles to complement them. And if only wear the tortoiseshell frame glasses may not look good.
Where to Buy Unbreakable Eyeglasses Frames?
From the above part, you have learned some unbreakable eyeglasses frames. So, do you know where to buy unbreakable eyeglasses frames? To buy them, Koalaeye Optical is strongly recommended. It is an online optical store, providing all kinds of eyeglasses, sunglasses and frames. So, from here, you can get the most durable eyeglasses frames.
Besides, these eyeglasses frames are stylish and come at a cheap price. If you buy them, the eyeglasses will be mailed to you with your great convenience. So, if you need unbreakable eyeglasses frames, try Koalaeye Optical.
The inadequacies of bifocals
The field of vision is smaller than that of the single vision lens, especially for the close view. For example, reading and reading newspapers need to make it coordinated with the head movement, there are optical defects of image jump and image displacement. There is a boundary, and it is easy to be seen that wearing a bifocal lens exposes age. Bifocals clearly demarcate the near and far regions, affecting appearance and vision. And when far view and close view change, the objects will jump. Because most myopic patients have a lag in the adjustment response, wearing bifocal lenses not only does not delay the development of myopia but has side effects. Therefore, bifocals are not suitable for teenagers to control myopia, and only a few special patients need to wear bifocals.
Kirkland Signature™ HD Digital Progressive Lenses
They use the latest lens manufacturing technology to provide high-definition vision at any distance. Giving you sharper vision in all conditions, all lenses have anti-reflection treatment, and they have superior scratch resistance and superior quality. The lenses help provide a greater reading area and less distortion than standard lenses. And they give each lens a cosmetically attractive appearance.
Is there any relation between lens refractive index and lens definition?
First of all, in reality, from the point of view of the immediate situation, there seems to be no correlation. The refractive index is mainly related to the speed of light transmission into the lens. High refractive index lenses can be made thinner, lighter, and the technology required to do this is more sophisticated, so high refractive index lenses are more expensive. But does a high refractive index make the lens clearer? The higher the refractive index of the lens, the lower the Abbe number. The Abbe number is a very important parameter we use to measure the sharpness of the lens, which means that if the refractive index of the lens is high, that is to say, the sharpness of the lens is lower. If you have higher degrees, you can prioritize thinness and choose a lens with a higher refractive index, but don't overdo it.