About celluloid glasses
In 1929, the first large-scale production of sunglasses made of celluloid was made by SamFoster, an American who ran a women's accessories company facing bankruptcy and made it convenient to use the injection molding technology used to make hairbrushes. Sunglasses made of celluloid were sold on the beach of Grand West, New Jersey, and became very popular. Indeed, celluloid glasses were once popular because of their high-cost performance, but celluloid gradually faded out of people's eyes due to its poor chemical stability, flammability, and other shortcomings, with the emergence of new materials for glasses.
Colored translucent frame
Colored translucent lenses have been popular since 2016. Some stars like a warm tan lens. Besides translucent lenses, what's popular this year is that the frames are made in a colorful translucent style. Wearing them can automatically cool down. Stella Mccartney 2020 spring/summer sunglasses are designed with colorful translucent material and a thick frame. In addition, a metal chain is added, which is all the popular elements this year.
The superior properties of titanium glasses
They are light, around 40% of stainless steel. The hardness is high, about twice that of stainless steel and common steel, twice that of iron, and six times that of aluminum. In a world of ultra-low temperatures, titanium becomes harder and more superconductive, while steel becomes weaker and less capable. They have corrosion resistance, with no rust. Titanium does not rust in the sea for five years, while steel corrodes and deteriorates in seawater. The thermal conductivity of titanium is about the same as that of stainless steel. They are non-allergic materials. Titanium is a harmless material to the human body. More because it does not have an allergic reaction to the human body, it is one of the few metal materials used in medical science.
Why is a prescription for glasses different from a prescription for contact lenses?
The frame glasses degrees are the optometric degrees of the eye, and the difference between the frame glasses degrees and the contact lens degrees is mainly due to the different contact distances between the two lenses and the eye. Usually, degrees of contact lenses and glasses need to be converted by a professional through vertex diopter. The conversion formula is Fc=Fs/(1-d×Fs). In the formula, Fc is the diopter of contact lens, Fs is the diopter of glasses frame lens, and D is the distance between frame glasses lens and cornea. Assuming that the prescription of frame glasses is -4.00d and the distance between lens apex is 12mm, the prescription of contact lenses is -4.00/ [1-0.012×(-4.00)] = -3.82d.
The shape of the lens is also important.
Aviator and cat-eye glasses should be avoided, as both will cut off the base of the prescription, resulting in poor reading vision. Instead, they should opt for shorter frames with rounded edges, such as bull horn frames, vintage wingtips, round frames, and oval frames.
Can Pinhole Glasses Improve Your Vision?
The most important question may be whether the pinhole glasses improve your eyesight and some people may have this trouble. Some people say pinhole glasses can improve the vision of nearsightedness or astigmatism. But there is no evidence to prove that.
Although pinhole glasses can improve vision to some extent, they are not practical for everyday use. Pinhole glasses are designed to block part of your direct vision and restrict peripheral vision. They would cut the amount of light entering your eyes so as to reduce the visual quality of an image. Hence, it would be not recommended to wear pinhole glasses in daily life.
How Do Varifocal Lenses Work?
Varifocal lenses work by changing power from the top to the bottom of the lens. Moving your eyes up and down, the varifocal lens will give you clear vision at all distances you need. This means if you are using a cash machine, you would be able to view the keys, screen, your card and then continue to walk down the street.