what is sph and cyl?
Sat, Apr 09, 22 By : Koalaeye
What kind of glasses are bifocals? Bifocals are mainly used in presbyopia correction, providing presbyopic opticians with a clear vision for both near and far use in one pair of glasses. The bifocal lens can be divided into two separate areas, with the upper part of the lens providing clear distance vision and the lower part providing clear near vision. The two regions of the bifocal lens provide different refractive forces, and the difference between these two refractive forces is...

What kind of glasses are bifocals?

Bifocals are mainly used in presbyopia correction, providing presbyopic opticians with a clear vision for both near and far use in one pair of glasses. The bifocal lens can be divided into two separate areas, with the upper part of the lens providing clear distance vision and the lower part providing clear near vision. The two regions of the bifocal lens provide different refractive forces, and the difference between these two refractive forces is the reading proximal addition, which compensates for adjustment during presbyopic reading.


What are blue light blocking glasses?

As we now spend more and more time on the screen, it is particularly important to pay attention to the effects of blue light. Approximately six out of ten adults will experience digital eye fatigue after using the device for more than 2 hours. Symptoms of digital eye fatigue include headaches, blurred vision, and dry eyes. The technology of blue light blocking glasses can effectively block part of the blue light damage to the eyes, reduce the visual fatigue caused by staring at the electronic screen for a long time and can also reduce the radiation and damage of ultraviolet rays to the eyes. However, the most important thing for eye protection is development. Good eye use habits, close your eyes regularly, and let your eyes rest.

Blue light blocking glasses are glasses that the manufacturer claims can filter out blue light. The lens of this kind of glasses has filter material or surface coating, which can block part of the blue light. People who believe that their eye and vision are damaged by blue light exposure may wear them to reduce blue light exposure.

Blue light is a short-wave blue light in the color spectrum visible to the human eye. Its wavelength is in the blue part of the electromagnetic spectrum, roughly 400–500 nanometers. Researchers believe that peak light damage occurs at approximately 440 nanometers. Computers, laptops, tablets, smartphones, and general lighting can all expose the eyes to blue light.



What Are High Index Lenses?

High index lenses are eyeglasses lenses that are designed to be thinner and lighter than regular lenses. High-index lenses have a high refractive index than their conventional counterparts. High index lenses are recommended for people who have significantly high refractive errors and strong prescriptions for nearsightedness, farsightedness or astigmatism.

High index lenses are thinner, lighter and more appealing than standard lenses, but they come in several different indexes such as 1.67 high index lenses and 1.74 high index lenses. In this post, we will focus on the 1.67 high index lenses and 1.74 high index lenses.


Sunglasses For Fishing - Ray-Ban

Ray-Ban was founded in 1930 in the United States. It is the inventor of the world's first sunglasses and is known across the world for it. It is treated as a symbol of American culture. ?Since its inception, Ray-Ban has been focusing on the development of sun-blocking products and integrating a lot of high-tech into them, committed to providing the best vision protection for modern consumers.



The Customization of Glasses

For the first time, you must go to a professional medical institution for medical optometry. Before the age of 12, you should dilate mydriasis and optometry. After the age of 12, you should decide whether to dilate mydriasis and optometry according to the specific situation of the eyes. The lens must be smooth, transparent, without bubbles and particles, with a uniform texture. The hanging ear of the temple should be attached to the outline of the outer ear, and the tightness should be moderate, so as not to slip.


Are the glasses purchased online of good quality?

Always, there are some people who question online shopping, whether the quality of the glasses purchased online is up to standard. Then I have to ask, is the quality of the glasses bought in the physical store good? Most people do not have the ability to judge the quality of glasses. It can be said that they decide which to buy based on an inexplicable idea. Therefore, for those who do not understand glasses, the quality of the glasses purchased online is not a question we should consider. In my personal experience, there has been no quality problem with the glasses purchased online, and for the same price, the glasses purchased in physical stores are much worse than those purchased online.



About Prism Glasses

The refractive index of the same medium is different for different colors of light. Different colors of light travel at different speeds in the same medium. Because the same medium has a different refractive index for various monochromatic light, and the deflection angle of each monochromatic light is different when passing through a prism. Therefore, white light through a prism will separate the monochromatic light, known as dispersion. What is the prism effect of glasses? As long as there is a deviation between the visual channel of the eye and the optical center of the lens, it can produce a prism effect. Therefore, the severity of the prism effect can be used to measure whether the glasses with the correct prescription are processed correctly and reshaped correctly.

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