The Disadvantages of Polycarbonate Lens
In this section, we will show you the disadvantages of polycarbonate glasses.
First, the polycarbonate lens is expensive than other regular lenses. It can cost up to double the price of regular eyeglasses.
Second, compared with high-index lenses, polycarbonate glasses have a lower abbe value, which is used to measure the dispersion of light for different eyeglasses lens materials. Polycarbonate lens rates lower mean they have the potential to cause slight chromatic aberrations in your peripheral vision.
Third, compared with Trivex lens, polycarbonate lens has bad durability since they are thinner and lighter.
What are prism glasses?
What is a prism? A prism is a solid object with a cross-section along its entire length. If you cut across something, you'll come across a section that's been cut, and that's a cross-section. The upward section is a prism. If you have double vision, you can add a prism prescription to the lens to form prism glasses. It can help keep your eyes focused and greatly improve your vision. In most glasses, prisms are used primarily to change double vision and are useful for image correction. They can aid in position correction.
How long does it take to get used to progressive lenses?
Because the adjustment of each eye is different, so there will be some differences in the adaptation period. It usually takes about two weeks to get used to it. Probably many young people are familiar with this kind of lens, so they adapt to them for only a week or so and can restore the normal visual effect. If it's been two weeks and you still feel that you can't see clearly, or you have the feeling of nausea, etc., then you need to test and adjust. You need to go to the hospital to see the specific case, to find out whether it is a quality problem of the sunglasses, or there are some artificial reasons. If there is a problem, we should also replace the lenses in time, otherwise, it may lead to the problem of visual fatigue. Therefore, it is still necessary to promptly confirm the case of optometry, and then replace the appropriate glasses.
About the early domestic anti-reflection coating lens
Chinese coated lenses appeared in the mid-1980s. At that time, Europe (such as France and Germany) and Asia (such as Japan, Singapore, and Taiwan) had already launched coated lenses to the market, and the grade of lenses was evaluated based on the quality of the anti-reflection effect. Among them, Germany and France were the two leading countries in technology. Technically, the use of French original film material (referred to as H2) can reduce the effect by 99.98% (refers to the light transmittance, the same below). Almost you can not see the reflection, but the material is expensive. Therefore, the coating lens which is currently used in the world is born. The anti-reflection effect is controlled at about 98%, so the coating cost is greatly reduced. And it is accepted by consumers because it presents various colors, especially green. At the same time, because at the same time, it can be easily distinguished from non-coated lenses. It can reflect the high-grade film lens, and it is accepted by the sales staff.
When the titanium purity reached more than 99% of the titanium metal materials, they can be called pure titanium glasses. Many people may not know what pure titanium is. In reality, many famous brand glasses are made of this material. The frames made of pure titanium have the benefits of high melting point, light material, strong resistance to corrosion, and strong electroplating, to ensure the two important properties of beauty and durability spectacle frames.
What Strength Reading Glasses Do I Need?
What strength reading glasses do I need? You can choose the reading glasses strengths by age or you can also perform a reading glasses test. If you are aging from 40 to 44, the +0.75 to +1.00 dioptre power is recommended. If you are aging from 45 to 49, the +1.00 to +1.50 dioptre is recommended. Age from 50-54, recommended power is +1.5 to +2.00 dioptre. Age from 55-59, recommended power is from +1.50 to +2.25 dioptre. Age from 61-65, recommended power is from +2.25 to +2.50 dioptre.
If you find two different strengths of reading glasses are available, choose the lower power because too strong strength can cause discomfort compared to weaker powered glasses and can even lead to nausea and dizziness.
So, if you need a pair of reading glasses, try Koalaeye Optical, which is an online glasses store. It provides all kinds of eyeglasses, sunglasses and frames. You can choose the satisfied one from here.
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