What are keyhole glasses?
Keyhole glasses have a keyhole bridge. The keyhole bridge is shaped like a keyhole and is located on one side of the nose. Bridge glasses are one of the most beloved styles in the history of optics. The keyhole bridge has the shape of a keyhole. The keyhole bridge is arguably one of the most popular eyewear features. With the rise of acetic acid frames in the 1950s, keyhole glasses became widely popular. The ductility of the new material allows for a simplified manufacturing process, thus creating room for creative experimentation in the frame development.
Is the prescription for glasses the same as for contact lenses?
A prescription for contact lenses is not the same as a prescription for regular glasses. The two types of glasses are quite different because glasses are located about 12mm from the eye, while contact lenses are located directly on the surface of the eye. If you want to wear both contact lenses and regular glasses, you'll need two different prescriptions. Contact lenses are worn in the eyes, and the frame is at a distance from the eye, although the distance is not large, definitely can affect certain degrees.
The design evolution of progressive lenses
Spherical and aspheric designs
The design of the front surface of the far-use area of the early progressive lens is similar to that of the ordinary spherical single vision lenses, so it is called a spherical progressive lens. Since 1974, the front surface of the far-use region of the lens is designed to be aspheric by designers, which not only reduces the peripheral aberration but makes the lens thinner, lighter, and less powerful.
Hard and soft design
For hard design, the channel is short, and the gradient is large. The near-use area position is high. The effective visual area of remote and near-use areas was larger. Peripheral astigmatism is relatively concentrated. Because surrounding astigmatism increases rapidly and the distribution is dense, the curve effect is more obvious. The gradient area is narrow. It is more difficult and takes longer for wearers to adapt.
Lenses with soft designs have slower gradients, longer gradients, and wider gradients. The angle of rotation of the eye from the far area to the near area is greater. It's easier to get used to. Compared with the hard design, the effective visual area of the far and near use areas is smaller, and the location of the near use area is lower.
Single, diverse, and individualized design
Initially, the progressive lenses used a single design, in which each basic curve was scaled equally and a luminosity combination was added within the range of its semi-finished lens blanks. The steepest base curve uses the same lens design as the flattest base curve. Lenses designers quickly realized that the overall performance of the lens could be improved by microcustomizing the lens design, leading to progressive lenses with multiple designs. This kind of design is called diverse design. By the mid-1990s, there was the emergence of individualized lens designs. In addition to using different gradients, these first individualized lens designs used steeper baseline curves with a slightly larger approach area to compensate for increased magnification and reduced field of view.
Symmetrical and asymmetric design
There is no difference between the left and right eyes in the symmetrical design of progressive lenses. As the eyes turn inward when they see near objects, the gradual gradient area gradually tilts to the nasal side from top to bottom, so the left/right progressive lenses should be rotated clockwise/counterclockwise respectively during processing. An asymptotic lens with left and right eye divisions is called an asymmetric design. The gradient is gradually and moderately inclined to the nasal side from top to bottom. The refractive force, astigmatism, and vertical prism of the two sides of the left and right gradient of the asymmetric design lenses are basically similar. At the same time, considering the characteristics of eye movement parameters in binocular vision, the peripheral aberrations of the corresponding positions of the left and right lenses were appropriately balanced to improve the visual effect of the wearer.
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 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.
How to Get Used to Progressive Lenses?
It is common that your vision may change when you are over age 40. You can find it is happening when have to hold your favorite book, the daily newspaper, or a restaurant menu farther away just to read it. This is an eye condition called presbyopia. It is normal and almost all of us get it as we reach middle age.
This eye condition often can be corrected by progressive lenses which allow you to see objects from far to near clearly. With progressive lenses, you do not have to switch your glasses to see far or near objects frequently.
However, since progressive glasses have three different prescriptions in one lens, it may be difficult for some people to adapt to the new ones. So, in this post, we will show you how to get used to progressive lenses.
How to Keep Glasses from Slipping
As for how to prevent glasses to slide down your nose, you can wear your glasses with a combination of material flexibility and friction. At the same time, you can also try some hacks or use some accessories to keep your glasses from slipping down your nose.
Eyewear Bands
To stop glasses from slipping down nose, you can use eyewear bands. These bands will prevent your glasses from marking them safe on your nose. The eyewear bands are great for stylish eyeglasses, reading glasses and wooden sunglasses. The length of the bands is adjustable to fit your head and neck.
Frame Tightening
To prevent glasses from sliding down your nose, you can choose to tighten your frame. You can ask the optician at the local optical store for help. However, after a while, the glasses will become loose and start to slide down again. So, you need to try tightening the frame again.
Eye Shadow Primer
As for how to keep glasses from slipping, you can use the eye shadow primer. You may feel strange when hearing the eye shadow primer trick. It is a popular one. Using the eye shadow primer on the bridge of your nose, especially where the nose pads come in touch, will prevent any slips. But this way also comes with some inconvenience because it requires you to do that every day.
Glasses Chains
To stop glasses from slipping down nose, you can use some glasses accessories, such as glasses cords and chains. With them, not only do they help your eyewear stay still, but you won’t have the risk of them. The glasses chain helps you to put hen on and off whenever you need them and stop your nose from slipping from your nose.
