The refractive index of the lens is related to the thickness of the lens.
The main factors that determine if a pair of finished glasses are beautiful, portable, and comfortable depending on the thickness and thinness of the processed lenses. Depending on the material, the index of refraction is different. If you just look at the refractive index, the higher the refractive index at the same degree, the thinner the lens will be. The thinner the lens will be, and the more beautiful the lens will be. However, the higher the refractive index, it is not the better. You can choose the refractive index lens suitable for yourself. But the refractive index is not the only factor that determines lens thickness. Think about the distance between your eyes and the size of the frames you choose, which can affect the thickness of the lenses you match. The larger the pupil distance, the smaller the frame, and the thinner the lens.
What Are Varifocal Glasses?
Varifocal glasses, also known as varifocals, varifocal lenses, PALs, or progressive lenses, have a gradual change in strength from the top of the lens to the bottom with multiple focal points in between. This allows you to see all distances and focus points through just one lens. Varifocal lenses are typically used when you have two prescriptions, one for distance and one for reading.
There are three regions of a varifocal lens which are distant zone, intermediate zone and, near/reading zone. Usually, the upper portion of the varifocal lens is the distant zone and the bottom portion of the varifocal lens is the near or reading zone.
One of the benefits of varifocal glasses is that you do not need to prepare 2 separate pairs of glasses or need to switch between frames for different vision needs.
Why do nose pads turn green?
Because there are copper accessories in glasses. And the copper and sweat mix for a long time, so it will corrode and rust. The greenness is the mixture of copper salt (copper rust) produced by the copper element in the coating and inorganic salt in sweat and grease dust. The color of copper is green, so is the dirt. If you sweat a lot and the lens bracket is metal, the nasal bracket silica gel is easy to turn green. This is usually due to oxidation caused by the combination of nickel with the natural oils in the skin. Your nose is usually the oily part of your body. The oil in the nose mixes with sweat and then oxidizes the metal. Glass frames are usually made of a kind of copper called Monel. Monel is an easily corroded metal that does not react to many chemicals. It's skin-friendly. The only downside is that it turns green when it rusts.
The advantages of metal frames
Its advantage is that the lens is fixed firmly, not easy to fall off. But the weight of the glasses increased slightly compared to the other frames. Full-frame glasses give people a sense of calm. The frame can cover the thickness of the lens very well, suitable for people with high degrees.
The weight difference between pure titanium frames and titanium frames
Titanium frames are slightly heavier than pure titanium frames, but they are both high-quality materials, so they are more comfortable on the outside. The specific gravity of pure titanium is generally 4.5, while titanium alloy is 8.9, which means the material is equivalent to half of the titanium alloy. So the frames are lighter in your hand.
Superior properties of titanium alloy
The specific strength (strength/density) of titanium alloy is far higher than other metal structural materials, which can produce high unit strength, good rigidity parts.The engine parts, frames, fasteners, and landing gear are all made of titanium.It can still maintain the demanded strength at medium temperature and can work for a long time at 450 ~ 500℃.
Confirm the optometric data
It is necessary to confirm the accuracy of optometric data. If you stay up late or look at the phone or computer for too long before the optometry, leading to visual fatigue, it will increase the degree. But if you can let your eyes have a good rest, and then take optometry, the degree may be restored to the original situation, so you need to know the state of optometry, to check if it really had increased in degrees. The main purpose of progressive lens is to use it for people who have bleached eyes and often take off the lens.
