Single Vision vs Progressive: What Are Their Differences
In this part, we will show you some differences between single vision and progressive lenses. They differ in several factors, so here we will compare them one by one.
Progressive lenses generally have their reading zones just in the lower half of the lenses, while single vision glasses have the reading power all over the lens. So if you are working on something above your head and you need to see some small details, the progressive lenses will not work. And you can not see through the reading zone in progressive you need to switch to single vision reading glasses.
Single vision glasses are cheap than progressive lenses. Compared to progressive glasses, single vision glasses hold way fewer distortions in the periphery. So, there is no need to customize the lens design to the max. In addition, single vision glasses are often available in the optical store while the progressive often needs to be produced for you. In other words, the delivery time of single vision lenses will be shorter for you.
You can use your progressive glasses optimally just in an upright posture. As soon as you lay down on your couch, this will lead to blurry vision. The reason is your changed position which forces you to look lower through the lenses on the screen. However, with single vision glasses, you can change to an upright position and it would not be a problem anymore. You can position yourself on your couch as comfortably as you want and you can still see clearly with your single vision distance glasses.
There are three processes for resin-changing lenses.
The incorporation method, known as bulk polymerization, is similar to the method of glass lens, that is, one or more photochromic dyes are directly incorporated into the polymer monomer of the substrate for bulk polymerization, and the lens formed after curing will change color. Discoloration dye is completely integrated into the resin lens substrate, so the lens made of color persistence is very good.
The uniformity of discoloration and the depth of color after discoloration are highly related to the thickness of the lens. Because the thickness of the lenses at all levels is different, there will be a color difference between the depth of discoloration and the uniformity, and the uneven phenomenon of high brightness is more obvious.
The film type is known as the coating method. It is the chromatic resin lens by coating or dipping in a layer of chromatic dye on the base of the resin lens. Because the coating covers the surface of the lens, the color uniformity is good. The coating, which is only about 0.05mm thick, does not provide enough molecules to make the lens dark enough, so the color is relatively less dark, and the discoloration lasts slightly longer.
Infiltration, known as the penetration method, is to use the principle of penetration, through the thermal diffusion method to make the color dye permeate the surface of the resin lens sheet material, with diffusion depth up to 0.15~0.20mm. The lens has a constant color change characteristic. There will be no inconsistency between the center and the surrounding color as the luminosity gets darker. The color-changing resin lens made by infiltration type has the benefits of uniform color-changing, small color difference, fast and thorough color-fading, which is the mainstream of color-changing technology at present.
Why are some glasses expensive and others cheap?
Lenses do not regulate vision, but some progressive lenses can help the ciliary muscles to adjust. The quality of the lens is mainly determined by the transmittance, the surface, the aspherical surface, the refractive index, the coating quality.
The higher the refractive index, the thinner the lens, and the more expensive the price, for some people with high degrees, the lenses also play an aesthetic role. Commonly used are green film, and some are purple film, gold film, etc. How much cheaper is a relative number, and there are many other factors to consider besides price.
What Are Computer Glasses?
Computer glasses or glasses for computer are prescription glasses that are designed to wear when doing computer work. They allow you to focus your eyes on a computer screen. There are other activities such as playing piano or shooting requiring a similar custom fitting.
Glasses for computer use are also known as blue light glasses. They block blue light that causes eye strain due to prolonged viewing of digital screens. Blue light is part of the color spectrum, and everyone is exposed to it through sunlight.
The glasses for computer use have a shorter wavelength than other colors and are emitted by electronic devices such as smartphones, TVs, computers and more. The glare from blue light is what causes digital eye strain or other symptoms. But the glasses for computer can protect your eyes from the damage of the glare.
Depending on an individual’s vision and type of work, there are several options while selecting glasses for computer use.
Monofocal: Monofocal or single-vision glasses are designed for computer work so that they provide the appropriate optical correction for the working distance between the screen and the user’s eye. These glasses allow users to view the whole screen with a minimum up-and-down head movement. However, the disadvantage of the monofocal glasses is that both distant objects and reading materials that are closer than the computer screen will appear blurry.
Bifocal: When it comes to glasses for computer screens, the bifocal glasses would be a choice. Bifocal glasses can be prescribed so that the upper segment is set up for screen distance and the lower segment for work. The disadvantage of these bifocal glasses is that it will blurry if the objects are farther away than the screen.
Trifocal: These trifocal glasses for computers have lenses that combine a segment for far vision, another for near vision and the third one for at the screen distance. The disadvantage of these glasses for computer screen is the limitation to view areas.
Can you repair rimless glasses by yourself?
Splice the broken temple of the glasses into its original position on the glasses. Cut a piece of tape about 10cm long and pass it through the gap between the temple of the glasses and the base of the spring. Place the tape on the inside side of the glasses and tighten the other side with your hands. Then apply the outer tape to the temple of the glasses and press it down with your hand. Cut a piece of tape about twice the circumference of the bottom of the temple of the eyeglasses and stick it around the bottom of the temple of the eyeglasses. Cut a piece of tape about twice the circumference of the upper-middle part of the temple and use it to stick the top of the tape used in the first step. Then a piece of tape roughly twice the circumference of the middle leg of the glasses was used to tape the area between the two steps. Then repeat the previous step, and introduce another layer of tape from the gap on the outside of the adhesive tape. First, cut off a piece of tape as long as the temple of the glasses and stick the end of it to the bottom of the temple at an angle of about 60 degrees. Then tighten the other end with your hand, making it stick upward in a spiral until it covers all the tape in front.
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.
Can clear lenses be polarized?
At present, there are no clear polarized lenses. A polarized lens is a thin film vertically arranged with silicon crystal coating placed inside the lens, just like a shutter, which covers the parallel light and only allows the vertical light to pass through. In this way, the glare from all directions can be eliminated, so it is clear and comfortable to wear. Transparent polyamide, the material of nylon lens, is a new variety of polyamide. The material of the nylon lens is mainly transparent polyamide. Due to the effect of the light filter, only light from a specific direction is allowed to pass through the lens, which filters the dazzling light from the sun on the water, land, or snow very well. It can not only make the landscape soft, clear, and natural but protect the eyes to a certain extent.