About Costco
Costco is a members-only warehouse club dedicated to providing its members with brand-name goods at the best prices. Costco has hundreds of stores around the world, providing a wide selection of merchandise. And the convenient specialty departments and exclusive member services, all are designed to make your shopping experience enjoyable.
Disadvantages of Progressive Lenses
It takes time to adapt to the lenses. It can generate poor visual resolution (blur). There is also a geometric distortion of the field of view. Some of the problems with advanced progressive lenses occur when walking up and downstairs. Because the reading correction is at the bottom, the staircase may look like a rebound. However, this is all done to accommodate your progressive lenses, and within about two weeks the shortcomings should disappear. It takes some time to get used to progressive lenses. Changes in vision occur at the rim of the lens, leading to slight changes in peripheral vision. For some people, change is a little difficult. Because the first wear of progressive lenses may occur slight dizziness, shaky walking. One should be careful when they exercise or go Up and down the stairs. Because the sense of space changes, the distance judgment of the object, the sense of depth changes, people who first wear should not immediately drive or do strenuous exercise. When looking closely, the eyes need to turn down, they have mild discomfort in the eyes. The object becomes blurry when they look at it through a blurred area around the lens. Therefore, new wearers turn their heads more and turn their eyes less when they see things and try to use the far, near, and middle distance areas to see the object.
The Pros and Cons of Shopping Glasses Online
Brick-and-mortar stores rely on a few or a dozen a day to make a profit, so the unit price is higher. Online stores have low costs. The profit can be made by volume, so the unit price is much lower. This is the advantage of online stores. The disadvantage of online stores is that it takes a lot of effort to get an optometrist, but optometrists have varying levels and attitudes. As a result, the prescriptions we get may not be entirely accurate. This can lead to uncomfortable glasses. The physical store glasses can try on. Choosing online glasses is not convenient.
Consider possible uncertainties after the lens is installed.
Usually, in-store frames are made of plastic samples rather than actual lenses, so they weigh slightly less. However, it is necessary to consider the approximate weight of the lens in advance according to its own degree when trying it on, in case the weight is not suitable for real wearing. If the pupil distance is too small, it is not suitable to wear a wider frame. The machinist should strictly follow the left and right pupil distance instead of taking the average, otherwise, there will be pupil distance error in the left and right eyes, which will cause discomfort in wearing.
How do anti-blue light glasses protect the eyes?
The anti-blue light glasses available on the market, no matter what type, etc., are mainly the difference in anti-blue light effect, light transmittance, and frame, which will affect the cost of glasses. Obviously, the lens is the most important of these. I think that it is basically enough to choose 30% to 40% anti-blue light glasses. It is good to cut off the harmful blue light. It is not necessary to completely eliminate the blue light so that the chromatic aberration will not be too large, the light transmittance is better, and it also has a certain anti-blue light effect.
Of course, to protect the eyes, it is not enough to rely on anti-blue glasses alone. The effect of anti-blue glasses is mainly to reduce the probability of eye diseases, and can not effectively relieve eye fatigue. Normal people between the ages of 20 and 40 blink about 20 times per minute. When you open your eyes and stare at a computer screen that changes rapidly, the number of blinks will be reduced to 4 or 5 times per minute, resulting in serious insufficient secretion of scum and dry eyes. Therefore, no matter how urgent the work is, you must pay attention to the rest of your eyes, close your eyes regularly, use eye drops when needed, and reduce the brightness of the screen as much as possible when looking at the screen. When the brightness of the screen is significantly higher than the ambient light It is easy to cause eye fatigue. Try to use it as little as possible in the dark. To be honest, it is more important to develop a good eye-using habit.
What color coating is good?
The purpose of plating anti-reflection film is to reduce the reflection of light. But because it is impossible to be completely free of reflected light, there will always be some residual reflection on the surface of the lens that causes the visible color. Someone asks which kind of these residual color is best. It does not have a standard actually. It is mainly based on a personal preference for color. More on the market at present is green color. However, these residual colors can initially help us to judge the thickness of the film: when the film is thin (the thickness is less than 139nm), the reflected light will show light yellow, and when the film is thick (the thickness is more than 139nm), it will show blue-green. The current multi-layer anti-reflection film thickness is about 0.3μm.
What are the advantages and disadvantages of bifocal reading glasses?
The advantage of bifocal reading glasses is a large field of vision, and they can be used with the same pair of glasses to see far, near. The cost is lower. But different areas have obvious intervals, and the appearance is not beautiful. The middle distance is fuzzy. They need to adapt to the period. Bifocal reading glasses lens is divided into two parts, and the degree of the two parts is not the same. The upper part is the mother of the flat area to see far, and the next part is the child of the reading area to see near. There is an obvious interval. The appearance is not beautiful. There is no transition area between two different areas, so its vision is fuzzy, easy to produce a 'jump image'. Long-term wearing will make people dizzy or fall down when climbing stairs.
