How to Choose Reading Glasses?
Choose big frames the first time. When choosing reading glasses, you can choose the big frames for the first time. You may need larger glasses frames or lenses to really get the sweet spot of where the prescription is.
And if you have never worn glasses for eye conditions such as nearsightedness, farsightedness or astigmatism, it is likely you will be able to see well with non-prescription reading glasses. So, you can buy these non-prescription reading glasses.
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.
Titanium is currently too expensive to refine.
It is highly demanding in buckling, stamping, cutting, and welding. The extraction of titanium, like that of aluminum before the 19th century, was quite costly and produced in limited quantities, so it was used only in extremely important fields, such as aerospace, electronics, precision instrument manufacturing, and so on.
Contact Lens Materials - Non-HEMA materials
The non-HEMA materials are hydrophilic soft lens material, which does not contain HEMA components. They are stronger and more oxygen permeable than most HEMA polymers.
The water content of regular hydrogel lenses varies from 30% to 58%. When oxygen passes through the hydrogel, it needs to be carried by water molecules in the material. Therefore, the higher the water content of the lens, the higher the oxygen permeability value. The softer the lens, the more comfortable it is to wear, which is conducive to the metabolism of the cornea. However, at the same time, the higher the water content of the lens, the faster the water evaporation, easy to dehydration, and easy to cause dry eyes. A lens with high water content has low material density, poor durability, and easy breakage, so they are suitable for making lenses that are frequently changed or discarded. On the contrary, the lens with low water content has good formability, easy operation, durability, and is not easy to dehydrate and cause dry eyes.
The categories of rimless glasses
Rimless glasses can be divided into metal rimless glasses and plastic rimless glasses according to the material. According to the metal category, they can be divided into nickel-copper alloy, memory titanium alloy rimless frames.
According to the elastic order of the frame, the softest and elastic kind is the plastic rimless glasses. The benefits are the lightest weight and the lowest price. The disadvantages are the short service life, faded look after the sun, and single appearance, which are suitable for children or teenagers in the stage of corrective treatment. The second elasticity is the memory titanium alloy rimless frame. They use aviation metal titanium as the raw material, suitable for people with sensitive skin, and have lighter quality, better durability, more styles.
Oval frame
Soft and smooth lines, implicit and introverted, reflect the gentle and quiet fair maiden style. It seems that the first pair of glasses worn by everyone who is nearsighted is oval, basically in high school. It seems to have a student era of green implicit, quiet lady. Even in middle age, there are a lot of people who will choose a lot of beautiful styles of oval frames. It seems that in their hearts, they all want to stay young forever.
Sunglasses For Fishing - Polaroid
Polaroid, founded in the United States, is the inventor of the world's first polarized glasses. Polaroid is the maker and leader of polarized lenses. ?Polaroid lenses are widely used in fishing, driving, labor insurance, medical, aircraft pilot, and scientific research. ?It enjoys a high reputation in the market and is loved and respected by countless consumers. Its industry covers more than 0 countries and regions in the world, and many big stars are her loyal fans.
