Why do spectacle frames rust?
Before solving this problem, we can first understand the causes of rust spots on the frames and skin allergies due to rust spots. Many alloy products in daily life contain nickel, and direct contact with the skin will cause allergies to sensitive people. The temples and nose pads are the parts that contact the skin with a large area, especially the outer surface of the metal frame and the interior of metal containing a large amount of nickel. Through contact with the skin and erosion of sweat, the appearance of rust spots and skin allergies are caused. Once allergy occurs, it will cause contact dermatitides such as redness, swelling, itching, and yellow water on the surrounding skin.
Types of aspheric lenses
There are two types of aspheric lenses: single aspheric surface (single aspheric surface for short, different from the outer aspheric surface and inner aspheric surface) and double aspheric surface (double aspheric surface for short). For the outer aspheric surface, convex is an aspheric surface and concave is a spherical surface. For the inner aspheric surface, a convex surface is a sphere, and a concave surface is an aspheric surface. In addition to correcting aberrations, the double aspheric lens also improves the effective field of vision compared to the single aspheric surface. When people's eyes look through the edge of the lens to see things, like driving when looking at the reflective mirror, it often affects vision because of the large aberration at the edge of the lens. Previous designs of aspheric plates have analyzed a single ray of light passing through the center of the pupil. Wavefront technology controls the entire beam of light passing through the pupil, eliminating high-order aberrations.
America's Best
America's Best is part of National Vision, one of the largest and fastest-growing eyewear retailers in the United States. It has more than 800 stores in 31 states and the District of Columbia and is adding more stores every year. The mission is to provide the best value for quality eye care and glasses at a low price that America deserves. All divisions of the company are committed to delivering this commitment to customers. Prices are usually lower than those of their competitors. They provide an extensive collection of designer eyewear frames like Ray-Ban. Due to bulk purchasing power, they can provide favorable price designer brand glasses. Each store is equipped with state-of-the-art optometry equipment to ensure customers receive the best eye care. They use cutting-edge manufacturing technology to provide customers with the highest quality products at the lowest price in the shortest time.
What is the best lens material?
The world's first resin lens was made of CR-39 material, and CR-39 is still the main optical lens material in Europe and the United States. After the end of World War II, people found that compared with glass, the main lens material at that time, the light transmittance of CR-39 is high, and it can block ultraviolet light. In addition, CR-39 can be dyed, not easy to fog, and has small dispersion (CR-39's Abbe number is 58) and other benefits.
How to choose blue light blocking glasses?
Nowadays, electronic products such as mobile phones and computers have become indispensable tools in our lives. While these high-tech products bring us convenience and fun, they also bring symptoms such as eye fatigue and myopia. Subsequently, blue light blocking glasses have also received everyone's attention. Anti-blue glasses are only suitable for people who use electronic products for a long time, not for people who are visually fatigued. Exposure to such unnaturally strong blue light for a long time every day, especially for teenagers and children, needs to pay more attention to the prevention of blue light. So, how to choose suitable blue light blocking glasses for kids?
Anti-blue light is necessary, but not all blue light can be filtered out, because blue light will interfere with the body's melatonin secretion after being over-filtered, thereby affecting sleep. Therefore, when choosing blue light blocking glasses, you should choose appropriately according to your own eyes.
For how to choose anti-blue glasses, consumers can distinguish from the color of the lenses. Generally speaking, a lens with a yellow color will have the effect of blocking blue light. But too dark lenses will affect the contrast sensitivity. Therefore, it is recommended that consumers choose moderately. In addition, consumers should also pay attention to whether the glasses products (lenses, frames) have conformity marks, etc. It is best to choose professional and well-known glasses shops to match glasses.
Do You Need Plano Glasses?
Many people choose to wear plano glasses or glasses without prescription just for cosmetic reasons, without any need for vision correction. Normally, glasses frames without a prescription come with a pair of cheap plastic demo lenses.
Since there is no corrective effect on plano glasses, some people choose wear plano glasses for protecting their eyes from dust, and other flying objects. In addition, plano lenses come in a variety of protective coatings - anti-glare, scratch-resistant, blue light coating, UV coating to provide all around protection to the eyes.
So, if you want to protect your eyes from some unexpected damage, you can choose to wear the plano glasses and they would not bring any damage to your eyes.
Tungsten Carbon Steel Spectacle Frame
Tungsten-carbon steel is an upgraded version of TR90. Its characteristics are basically lighter, softer, and higher in hardness than the original TR90. It is said to be the material softer than water, lighter than paper, and harder than steel. Tungsten-carbon materials are also called yellow materials in the glasses industry, and the terms of tungsten-carbon plastic are only for consumers because consumers do not know what they mean.
In terms of raw materials, titanium is the most expensive material, and the value of raw materials determines the final retail price of the glasses. The cost of tungsten carbon is slightly higher than the price of TR90 by about 20%, which is about the same as the value of low-end alloy glasses. The cost and value of pure titanium are 3 to 4 times that of TR90 and low-end alloy glasses, so the basic price difference between a pair of brand new pure titanium glasses and TR90 glasses is very large.
