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.
Why do spectacle lenses fog up?
The fog on the surface of the lens is essentially related to the saturation pressure and water vapor liquefaction. The air is full of water molecules, which are constantly doing irregular movements. When there is no temperature difference, water molecules keep hitting the surface of the lens and will keep bouncing off. The lower the temperature, the slower the speed of movement. Therefore, when water molecules hit the cold lens from the hot air, on the one hand, they move too slowly to fly out in time. On the other hand, because of the relatively low temperature of the lens itself and its vicinity, the water vapor will liquefy. As a result, more and more water will accumulate on the lens and form small droplets, eventually forming a foggy layer. As the lens heats up, the mist evaporates back into the air, and the fog disappears.
Characteristics of Carbon Fiber Glasses
Carbon fiber frames have pretty impact resistance. Carbon fiber is made of carbon, the core element of diamonds. It is ten times stronger than iron, and it weighs less than steel. The maximum stress it can withstand before breaking is 7 to 9 times that of steel. Carbon fiber is more resistant to corrosion than metals like titanium. It has high-temperature resistance, radiation resistance, good elasticity. Carbon fiber is not only flexible, but durable, so it won't break if you drop it. Carbon fiber has many benefits, including high stiffness, high tensile strength, low weight, high chemical resistance, high-temperature resistance, and low thermal expansion.
Why are eyeglass frames are so expensive?
Plastic frames are often used for rimless glasses, but they are not very resistant to corrosion and break easily. The plate is a new type of plastic, and it is light and has high hardness, not easy to deform, but the surface is easily corroded by sweat. TR90 has features of wear resistance, good chemical resistance, solvent resistance, weather resistance, not burning, high-temperature resistance. Plastic steel does not contain any metal, but it is a kind of high-strength molecular material, lighter than TR90. They have a higher level in corrosion resistance and strength and other aspects. The frames made of good materials are more comfortable, durable, and textured in daily wear, and will not cause skin allergies. Plate, titanium, TR90, alloy are the most used materials on the market at present. The price is in dozens of yuan to hundreds, thousands of yuan.
Sunglasses For Fishing - Molsion
The headquarter is set up in Xiamen, Fujian Province. ?Molsion?integrates a large number of fashion elements into the products, combined with the top materials, and strives to ensure the quality of the glasses while giving them a certain sense of design. ?The participation of top Italian designers brings a distinctive international vision. The design team captures the slightest trend changes with a keen fashion sense and makes each pair of glasses shape everything beautifully, along with a precise craft.
Choose blue light blocking glasses with guaranteed quality.
Because blue glasses is a kind of special care, which requires quality assurance. Wearing the unqualified glasses for a long time not only failed to protect his eyes against the blue glasses but can also lead to decreased vision. In severe cases, physical disorders can occur, causing dizziness, headache, and so on. So choose a big brand, guaranteed blue light blocking glasses, which can truly protect your eyes.
Zenni Optical
Zenni Optical is a company that sells eyeglasses online. Its mission is to provide stylish eyewear at affordable prices online. Zenni Optical sells prescription glasses, blue light glasses, and sunglasses, with a variety of lenses to choose from. You can order Zenni Optical glasses by selecting frames, lenses, and add-ons from the company's website. Zenni glasses range in price from $6.95 to $49.95. If you have a complicated prescription or add extra costs, the cost will rise to $100 or more.
