Single Vision Lens
Single vision is the most commonly used prescription lens. This lens type has a single field of view or a prescription ability of the entire lens and can be used to correct myopia (nearsightedness) or hyperopia (supervision). Some people need glasses to keep their distance and read. Instead of having a pair of single-vision glasses for each pair of glasses, bifocal or progressive glasses may be a more convenient choice. Unlike single vision, bifocal and progressive lenses are multifocal lenses with multiple focal points, such as distance and near distance. People whose prescription for spectacles list the numbers in the 'ADD' section require bifocals, progressive glasses, or reading glasses because your glasses need to add ADDitional to the distance prescription to see close distances.
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.
What Are Progressive Glasses?
Trifocal glasses and no-line progressive lenses are multi-focal glasses, meaning that their lenses offer multiple correction fields. Whether you have been wearing multi-focal glasses for a while, or you have just begun to look at options for correcting vision after 40 years old, you may have heard the terms trifocal or progressive glasses.
Progressive lenses offer a smooth transition from distance vision through intermediate vision to near vision, and they supply all the in-between corrections. Progressive lenses have three different viewing zones, as trifocal glasses do, and they have progressive powers of corrections, easing eye strain and providing the most natural vision correction.
Can you wear glasses with swimming goggles?
One potential solution to blurry vision while swimming is to wear prescription glasses under your goggles. While this can be effective in improving vision, the biggest problem is that if you wear glasses under your glasses, your goggles don't fit tightly to your face, which means your eyes get water. If you try to fix the problem by tightening the goggles around your glasses, you could break something that would cost hundreds of dollars to replace.
How to Adjust Crooked Glasses
If one side of your frame looks higher than the other, you need to adjust the arms of your glasses. So, how to adjust glasses?
If the right side is higher than the left, you need to gently bend the left arm down at the hinge or where the arm bends behind your ear. If the left side is higher than the left, so just do the same action on the opposite side.
When adjusting crooked glasses, you need to adjust frames a little bit at a time to avoid overcompensating and possibly damaging your glasses. You can run the arms under the warm water but do not running the warm water over the lenses because it will affect the lens coating.
Progressive lenses and single vision lenses
Single vision lenses are the most widely used optical lenses and are suitable for the general population.
Progressive lenses are suitable for below people.
① Myopia control lenses for teenagers. Progressive lenses are used to relieve visual fatigue and control the development speed of myopia.
② Anti-fatigue lenses for adults. Progressive lenses are used for teachers, doctors, people who use too much computer at close range to reduce visual fatigue caused by work.
③ Progressive lenses for Middle-aged and elderly people. A pair of glasses for middle-aged and elderly people to easily see near and far.
Westie Dog Eyeglass Holder
The spirit of Westie is captured by this adorable dog frame, which stands about 4.5 inches tall and can be fitted with glasses, sunglasses, and so on. This dog frame is a great choice for children's frames. It uses high-quality resin designed and manufactured in the UK. Each dog spectacle frame is hand-painted and comes in a gift box.
