Testing of aspheric lens
The optical axis of the optical center just overlaps with the visual axis of the eye, which is the most ideal state. Because the light from the edge cannot form a focus on the optical axis, when the optical axis does not overlap with the visual axis (the difference is greater than 2mm), such unclear and scattered imaging results will occur. When choosing frames and aspheric lenses, you need to ensure that they fit correctly, to achieve the best visual and decorative effects. Simply put, due to the special design of the lens, we found through a calculation that the optical center should move down 1mm higher than the pupil for every 2° increase in front inclination angle. Otherwise, the wrong pupil height will cause the lens to look like astigmatism, and cause discomfort. For glasses with aspheric lenses, there must be an inclination angle after wearing. The specific angle varies from person to person.
Why do nose pads turn green?
Because there are copper accessories in glasses. And the copper and sweat mix for a long time, so it will corrode and rust. The greenness is the mixture of copper salt (copper rust) produced by the copper element in the coating and inorganic salt in sweat and grease dust. The color of copper is green, so is the dirt. If you sweat a lot and the lens bracket is metal, the nasal bracket silica gel is easy to turn green. This is usually due to oxidation caused by the combination of nickel with the natural oils in the skin. Your nose is usually the oily part of your body. The oil in the nose mixes with sweat and then oxidizes the metal. Glass frames are usually made of a kind of copper called Monel. Monel is an easily corroded metal that does not react to many chemicals. It's skin-friendly. The only downside is that it turns green when it rusts.
Choose the right clear sunglasses for your face shape.
A clear eyeglass frame suits the person of different face shapes according to different shapes. For example, a heart-shaped face suits the clearest eyeglass frame, and a square face suits an elliptical transparent eyeglass frame. A round face suits the clear eyeglass frame with an outline. The long face suits the clear eyeglass frame with some width and so on. There are many kinds of clear frames, like oval, round, square frames, and so on.
When choosing clear frames, be careful to choose one that fits the shape of your face. Oval and the round clear frame are more suitable for heart-shaped faces, square faces, and long faces. People with round faces should avoid large frames, dark frames, and wide edges, and don't wear round or square frames.
How Do Progressive Lenses Work?
How do progressive lenses work? You may have this problem. As is well known, when you are over 40, your vision begins to deteriorate and you may suffer the presbyopia condition. So, with the progressive lenses, you can see at all distances with one pair of glasses. They start with your distance prescription at the top of the lens and increase as you move toward the bottom of the lens.
Then you move your head position to allow you to focus through different areas of the lens. Move your head upwards to see something in the distance, hold it straight for intermediate or arm’s length vision and down for near vision for objects that are close up.
In addition, progressive lenses avoid the visual discontinuity or image-jump when your eyes shift from one zone to the other in non-progressive multifocals since there are no distinct lines in progressive lenses.
Fetch Eyewear
With so many styles to choose from, trying on frames from the comfort of your home can help narrow your search for new prescription glasses. The Home Try On program makes it easy. Because all non-prescription glasses (including sunglasses and readers) are 100% returnable. The Home Try-On program will focus on customers who buy prescription glasses. Send the prescription to the appropriate email or upload it at checkout. After completing the $0.99 temporary licensing fee, your Try At Home kit is complete. This fee will be refunded to your card once they receive your kit.
Why can't you wear expired contact lenses?
Contact lenses have a throwaway cycle. If the contact lens has been opened, the shelf life of the contact lens is calculated from the day it was opened. Contact lenses have a life cycle. The life cycle is the shelf life of contact lenses. For example, if you wear daily contact lenses, you will have to throw them away. If you wear monthly contact lenses, they will have a shelf life of one month. Even if you wear them only a few times, you will still have to throw them away. The shelf life of contact lenses is calculated from the day the lenses are taken apart, not from the number of days they have been worn.
After the shelf life of contact lenses, there will be some cases like lens aging, hardening, lens discoloration, decreased transparency, lens deformation, thickening, an increase of lens protein, and other precipitates. The microbe is easy to deposit, resulting in poor oxygen permeability. If you continue to wear it, it is easy to cause inflammation of the conjunctiva and corneal hypoxia, and the comfort level will be much worse. It is suggested to analyze the case according to your own care. Once the contact lenses have the above cases, they should be replaced in time.
Service of GlassesUSA
Depending on your prescription, your glasses are possible to be delivered to your door within 10 to 20 business days. Glasses and contact lenses bought on the site come with a money-back warranty, free shipping, and return, and a 365-day warranty. GlassesUSA provides a two-for-one option. There are ready-made coupons.
