What Are Varifocal Glasses?
Varifocal glasses, also known as varifocals, varifocal lenses, or progressive lenses, have a gradual change in strength from the top of the lens to the bottom with multiple focal points in between. Unlike bifocals, varifocals glasses have no specific area of lens strength, but progressive lens zones.
As mentioned above, varifocal glasses have three different prescriptions in one pair of glasses, allowing you to correct near and far vision. So, they bring you great convenience since you don’t need to change the glasses frequently.
However, there are also some common problems with varifocal glasses and we will show you the disadvantages of varifocal glasses.
So, in the following section, we will show you the disadvantages of varifocal glasses.
What Should You Do If Your Glasses Are Broken?
Professional eyewear repair shops have professional repair tools. It's relatively easy to fix the bent frame by yourself. Still, there are reasons to get a professional to fix them. Your local eyewear repair shop can quickly reshape metal and plastic frames and make sure they fit. Many professional optical shops will make small adjustments free of charge. The frame is completely broken and requires special tools and skills to fix. Frames are too fragile to repair at home, and trying to do so could cause even more damage to your frames. The lenses are damaged and you may need to replace them. Make sure your prescriptions are up to date. If your prescription is not up to date, you need to schedule an eye exam before changing your lenses.
Disadvantages of contact lenses
They require more care than glasses. If you don't clean your contact lenses properly, or if you don't wash your hands before touching them, you could get a serious eye infection. Wearing contaminated contact lenses not only causes damage to your eyes but causes inflammation. If you have high astigmatism, your vision may become blurry when the lenses rotate. And there are a lot of contact lens health risks. There is a lot of news exposed that many informal manufacturers use fake or shoddy materials to make contact lenses, especially for the so-called beautiful contact lens, there are more risks in dyeing and health. The damage to the eyes is unimaginable.
OSKIDE night driving glasses
With excellent night vision, this product can provide you with clear vision when driving at night, on cloudy or rainy days. In addition, it can protect you from the sun's harmful rays and bright headlights. Made of durable materials, they are flexible enough to withstand strenuous exercise and high-intensity outdoor activities. Equipped with polarizing lenses, they reduce glare and improve clarity when bright lights may be distracting, so they are perfect for sunny days or night driving. And it has UV 400 UV protection function. It protects your eyes from harmful ultraviolet and blue light.
When were the first glasses invented?
No one knows when the first pair of glasses were invented, but we do know that the grinding techniques for making simple magnifying glasses have been around since 1000 AD, especially in regions where glasses were already produced (including northern Italy). The earliest artwork of glasses appears in the Treviso Cathedral fresco painted by Tommaso de Modena in 1352. There is reliable evidence that eyeglasses were invented in Italy in the late 13th century. The first pair we think of as eyeglasses appeared in Italian pizza in the late 12th century and looked more like two small magnifying glasses (made of raised glass) riveted together at the top of the handle. In 1266, The English Franciscan Monk Roger Bacon wrote about the scientific principles of corrective lenses, but there is no evidence that he applied this knowledge to the manufacture of eyeglasses.
The style of prescription glasses
Choose the material, and then choose the style. The width of the appropriate frame should match the distance between the two pupils to ensure that the eye can pass through the optical center when looking at things. Choose the right style according to your face shape. Generally follow the complementarity principle, such as choosing square frames for round faces and round frames for square faces. After choosing the frame, you should try it on for a while to see if the weight is appropriate and the style is suitable.
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.
