How do prism glasses work?
Prism glasses rearrange the images by bending the light and moving the images the eye sees to the desired position. They can align?with what each eye sees, eliminating the double image that the brain interprets. When the images seen by both of your eyes are rearranged, the light is redirected to the right position in the retina of each eye. The brain fuses these two images together to form one clear image.
How to choose the right glasses for myopia?
Nowadays, people are nearsighted, and they usually think of going with a pair of glasses. However, only from the media, we continue to see that there are substandard myopia glasses and frames in the report, so how should we choose when we buy glasses? How can I match a pair of suitable and high-quality glasses? Different glasses shops vary greatly from optics technology to the quality of lens frames, so different shops have different prices. Faced with a variety of glasses, how should we choose? Generally, we can look at these four standards. First, take a look at whether the eyewear company has obtained a production license for eyewear products. Second, see if the optometry equipment and testing instruments of the glasses companies have qualified marks. Third, see if the optometry and production staff are certified to work. Forth, look at whether the glasses have a conformity mark (certificate). The four certificates of eyewear companies are the prerequisite to ensure the quality of glasses.
3 Common Problems with Progressive Lenses
Though progressive lenses are popular to correct some eye conditions, there are also some drawbacks. So, in the following section, we will show you some common problems with progressive lenses.
Dizziness: the three different focal lengths of progressive lenses can make people susceptible to dizziness, as well as vertigo. From long to medium to short distance, the lenses offer a gradient of increasing strength. So, it would have trouble in adapting the glasses for the people who are wearing them for the first time. A common mistake is to look out of the wrong focal length, causing their vision to be blurry and lead to an overall feeling of dizziness.
Peripheral distortion: another common problem of progressive lenses is the way in which they blur peripheral vision. Most glasses cause an initial distortion to vision. However, the three different segments found in these lenses can make that distortion feel more prominent than other pairs of eyeglasses. And most people may need two weeks to adjust to progressive lenses.
Depth perception: Since progressive lenses provide three different prescriptions to see objects clearly for different distances, it is important that you need to move your head instead of your eyes when focusing on objects at different distances. Prior to adjusting to this little nuance, progressive lenses can cause depth perception to feel off.
From the above information, you have known some common problems with progressive lenses. So, you may ask how to adjust the progressive lenses. The most popular way is that you need to wear them frequently.
Features of progressive lenses
With the proper head position, the wearer can have a clear and continuous vision at all distances from the distal point to myopia through the progressive lens. When the eye moves from one area of vision to another, the eye adjustment process is natural and smooth, without any visual fluctuations. With natural vision and better adaptability, it is in line with physiological optics. The mid and near vision area is relatively small: Some wearers may feel that the gradient area of the progressive lens is smaller, which limits the width of the saccadic eye and requires increased head movement in order to achieve the same reading range. At medium and short distances, the wearer needs to coordinate certain head movements.
The anti-reflection principle of the anti-reflection film
Anti-reflection Coating, known as anti-reflection membrane, is called anti-reflection coating in English, or AR membrane for short. The basis of anti-reflection is the wave and interference of light. The principle is: Two light waves with the same amplitude and the same wavelength are superimposed, then the light wave amplitude is enhanced. The two wavelengths and amplitudes are the same, but the superposition of wavelengths with different wave paths (similar to dislocation) cancels each other out. Therefore, the anti-reflection film plated on the surface of the lens uses this principle to make the reflected light generated by the front and rear surfaces of the film layer interfere with each other, thus canceling each other and achieving the effect of reducing reflection.
What Do Trifocal Lenses Do?
Trifocal glasses can provide correction for some eye conditions including presbyopia and cataracts. Presbyopia often occurs in people who are between the age of 40 and 60. People’s eyesight starts to deteriorate and they are unable to focus at near. Wearing trifocal glasses can help correct blurred vision, eye strain, and headaches. The trifocal intraocular lens placed during cataract surgery can also resolve cataracts.
From above, you have learned some information about trifocal lenses. But what are the pros and cons of trifocal lenses? So, in the following section, we will focus on the advantages and disadvantages of trifocal glasses.
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