What are bifocals?
A bifocal lens is a lens with two focal points. Because of the imaging principle of the lens, even half of the lens can still present a complete image, and the two images do not interfere with each other. In the past, both short-sighted glasses and presbyopia glasses were called single-focal lenses, which had only one focus. Later it developed to the bifocal lens, and the same lens is divided into upper and lower two parts. The upper part of that lens is used when seeing far, and you look down when seeing close objects, just the reading distance, naturally used the second half.
Optometry for prescription glasses
The key prerequisite for proper glasses is accurate optometry. In foreign countries, professional optometrists are generally required to be qualified to issue prescriptions for optometry. However, this is not very standardized in China. Many optometrists have only been trained for a short period of time and do not have the basic knowledge of ophthalmology. For some complex situations, they may not give a proper prescription for glasses. Therefore, optometry should choose a qualified institution. If you are adolescents, people with high myopia, people with anisometropia, etc., you may need to dilate your pupils for optometry. It is best to go to the optometry center of the hospital for optometry
How to Tell If Your Progressive Lenses Are Correct?
When you can’t read with your progressive glasses, you can try this way. Hold something you want to read in your hands and lower your look with your eyes. But please note do not move your chin down as you look down. Then look down at something to read but do not lower your chin. Look at something you want to read. Rotate your head to the left and right and right with one eye at a time. If you can read in a rotated position, the reading zone is out of place. If you can’t read at all, the progressive glasses may be wrong.
Sunglasses for Fishing under $50 - Beishidun
The price is more favorable, and the function can be adjusted according to the strength of the sun's light. On sunny days, they can filter glare, protect the eyes from light stimulation. When they are worn on cloudy days, the lenses will lighten according to the light, preventing dimness of vision. ?And wearing comfort is also good. Traveling, climbing, driving, and so on can be used. ?As an emerging brand in recent years, the current user's popularity in the market is not small. In the design and functionality, they can meet the public, and at the same time, the cost performance is good.
Why should you choose thin lenses?
Regular lenses are great for low-prescription people, but for high-prescription people, high-prescription regular lenses are too thick and heavy, making them unattractive and have a poor wearing experience. For high-prescription people, we recommend that they choose thin lenses with a high refractive index because they are lighter and more attractive to wear. For any astigmatism above +3.00, we recommend 1.67 or 1.74 refractive index lenses because these lenses are aspherical in design, which means they are thinner, flatter, and lighter than standard spherical lenses, which reduces the magnification of your eyes to other people.
How do I know what size glasses frame I need?
With unified factory product size, why others can wear without problems, but there is a problem when I wear the glasses? There are differences between the contours of each person's face, including factors such as the width of the head, the distance between the ears and the corners of the eyes as the crow flies, the thickness of the bridge of the nose, and so on, which involves ergonomics. But there is one thing we can agree on. When people with the same ear distance wear the same type of glasses, they have different feelings, even if the arm length of the glasses is the same. People with fatter faces will feel uncomfortable. The face will be uncomfortable because the ear distance is the same, but the face width is not the same, resulting in an increased oblique distance of the temple, resulting in a sense of pressure.
It is very simple to solve this problem. You need to look at a variety of parameters in the frame of the glasses, including the total width of the frame, the length of the arm. These parameters will be reflected in a qualified spectacle frame.
Features of pure titanium glasses frame
Due to the lightweight (ordinary nickel-based alloy frame weight 48%-60%), high strength, corrosion resistance, surface easy coloring, beautiful and durable features of spectacle frame made of pure titanium, they have been loved by most consumers. But the elastic modulus of pure titanium is higher (about 120GPa). The temples of the frames made from them are not elastic enough. After wearing the glasses for a period of time, the temples of the glasses need to be adjusted due to the relaxation of the stress. The processing plasticity of titanium metal is worse than that of other metal materials, so the processing technology of its wire is difficult. The surface quality is difficult to control, and the technical content is high. The surface quality of pure titanium wire produced by a few domestic manufacturers is poor.
