Design principle of progressive multifocal lens
For the same piece of the lens, the top is used to see far, the bottom is used to see close. The upper and lower degrees are different.
There is not a sudden change in the distance degree fixed above the lens to the near degree fixed below the lens, but a gradual transition between the two through gradual changes in refractive power, which has special benefits over common bifocals or trifocal lenses.
Progressive lenses and single vision lenses
An optical lens that has only one luminosity on a single vision lens and does not have special functions.
The curvature of the front surface of the progressive lens increases continuously from top to bottom, and the refractive power increases gradually and continuously from the distance zone located on the upper part of the lens until the near zone at the bottom of the lens reaches the required near-use refractive power. A pair of glasses can be used. You can see far away, you can see close, and you can see objects in the middle distance.
GlassesUSA has a wide variety of glasses.
GlassesUSA has a large selection of frames to choose from. Their frames are classified by gender, designer, color, shape, and trend. In addition to sunglasses and sports glasses, there is an area for children's glasses. GlassesUSA has cheap options and expensive frames. To mark the launch of 3D-printed glasses, GlassesUSA is giving consumers the opportunity to design their own frames for an opportunity to win a $300 GlassesUSA gift card.
How do myopic glasses work?
The formation principle of myopia is that when the light from the outside world enters the eyeball, it is refracted by the eyeball's refractive system and cannot be accurately imprinted on the retina. The image is in front of the retina. If a concave lens is placed in front of the eye before the light enters the eye, it shifts the focus of the myopic eye from a point in front of the retina to the back, so that it lands directly on the surface of the retina. When parallel light passes through a concave lens, it diverges, meaning that it has already diverged once before entering the eye and then is refracted normally by the eye's refractive system. When the light is refracted through the eyeball, the distance of the image will be longer. So the distance of the image will be correspondingly pushed back compared to the non-divergent light. But it will just fall on the retina, and the image will be accurate in the right place.
How to determine whether progressive lenses are worn correctly?
Once your glasses are back from the lab, the optometrist will let you put them on for an audition and make final adjustments to make sure they fit. If the prescription is not in the center of the lens, it will make it difficult for you to see clearly. The key is that the lenses match the wearer's eyes, especially the pupils. Before ordering a new lens, the optometrist takes two measurements: pupil distance and fitting height.
The Identification of the Quality
The frame that has good elasticity is usually of better quality. The frame that has a smooth and shiny coating is better in quality. If the solder joint is smooth, small, and uniform, the quality is better. The parts of the sunglasses are assembled closely. The size and shape of the left and right lens must be the same, and the bridge of the nose must be symmetrical.
Choose the cost-effective glasses.
Choose your favorite glasses online. Open the shopping website, and select a store with high credibility. Choose your favorite glasses according to the style, lens, frame color, blue light blocking, radiation protection, and other factors, and then communicate with the customer service about the thickness of the lens and other specific details. If you see the frame is not suitable for yourself, you can communicate with customer service ahead of time to see whether you can buy the frame to send freight insurance. If it is not suitable, can we return it for a refund? To buy a store with a high reputation, you can look at the store's good comments and bad reviews. Talk to customer service. Sometimes there are hidden discounts.
