What Are Trifocal Lenses?
When you are over 40 years old, your eyes may become old, too. Your corrective lens requirements may become increasingly unique, Most people are familiar with bifocal glasses but unfamiliar with trifocal glasses. So, in this post, we will show you what trifocal glasses are.
Trifocal lenses have three different corrective lenses within one lens to offer you intermediate, distance, and near correction, all in one pair of glasses. The varying levels of correction cab are laid out in a couple of different ways to ensure the layout suits your unique vision needs and comfort level.
The near vision is to correct close-up vision, the intermediate vision is often used for card playing and staring at the computer screen fall with this range of vision, and the distance vision is often used for driving or looking at a whiteboard.
Glasses are used as accessories.
Glasses can be used to outline your face. Most glasses have a positive effect on the temperament and image of the person, provided that the choice is proper. The function of the spectacle frame, in addition to its supporting the lens to form glasses to wear on the eyes of the people to play a support role, also has a beautiful, decorative role. Modern fashionable person emphasizes glasses should have harmony with the facial makeup and dress of person, reflecting social class, high learning, elegant fashion, and so on. When the spectacle frame is worn by people in the streets and alleyways, those who are not nearsighted begin to pay attention and feel that wearing a chic spectacle frame is a very fashionable behavior.
Frame Selection of Progressive Sunglasses
Choose a proper frame range. Only if the frame is not very large and beveled, the frame can be very flat. Because the distance from the glazed to the optical center of a progressive multi-focus lens is 19-17 mm, and the distance between the edges of the frame will be no less than 28 mm if the area inside the lens can be used at close range while maintaining the far sighting field.
Choose clear glasses for kids to keep safe.
Safety is very important no matter in what aspect, glasses are no exception. Especially for children, they are more active. The lens is best made of PC, and the frame is best made of materials with high toughness, such as TR90. Service fixed number of years of this kind of picture frame is long.
Where did the glasses emoji come from?
The glasses emoji was approved as part of Unicode 6.0 under the name Glasses in 2010 and was added to Emoji 1.0 in 2015. Unlike the bespectacled 'nerd face', which is often used to suggest a cool sense of fashion. Just clicking on a few posts with the emoji is enough to make a person want to follow the eyeglasses fashion trend.
The refractive index of lens
Refraction law is discovered by Dutch mathematician Snell.It is the law that determines the direction of refracted light in the phenomenon of light refraction. When the light from the first medium (refractive index N1) into the second medium (refractive index N2), part of the light from the first medium into the second medium at the smooth interface will be refracted. The index of refraction is the ratio of the speed at which light travels in a vacuum to the speed at which light travels in the medium. For glasses lenses, the higher the refractive index, the thinner the lens, that is, the lens with the same center thickness and the same degree, the lens with the higher refractive index has thinner edges than the lens with the lower refractive index of the same material.
Identify the frames of discount glasses
Electroplating spraying refers to metal frames, all need to be plated on color. Spraying, the quality of this process, determines the quality of the frame. Glasses are not high-tech, but details like hinges -- the joints that open and close -- make a big difference between good and bad. The little screws inside, about four of them (hinges and nose pad), are important.Silk screen printing or laser engraving refers to the above logo or data, some of the silk screen, easy to sweat and fade, does not affect the use. Some laser engraving, basic will not fade, so, look at these details, can probably judge the stand or fall of the frame.