what is single pd or dual pd? | KOALAEYE OPTICAL

what is single pd or dual pd?

How to Choose Glasses for Big Heads?

In this section, we will show you how to choose an eyeglasses frame for large heads. If you do not know how to choose, keep on your reading to find some solutions.

Rectangular frames: Rectangular frames add angle and can slim down the appearance of a larger head. So, if you have a big head, try the rectangular frames glasses.

Oversized frames: if you have a big head, the oversized frames would be a good choice. Oversized glasses will balance out your larger features.

Wayfarer frames: whether your style is retro or geek chic, you will find a perfect fit in trapezoidal wayfarer. The thick angular frames offset rounder cheeks and draw attention down from the forehead. So, if you have a large head, try this style.

When choosing glasses for large heads, you should also find the right shape and color for your signature look and style. While there are a lot of glasses styles for big heads, you should consider glasses with long enough temple length, the length between the hinge of your frames and where they bend around the ear. This measurement is critical for overall comfort, especially on your temples and near your ears.

So, from the above information, you have learned how to choose glasses for big heads.


Disadvantages of Progressive Lens

There are deformation areas under the left and right sides of the lens, which make the image blurry and irregular. It takes 1-3 weeks to get used to it. In addition, it has a narrower field of view in the near and middle distances, and long-term concentration on the narrow focal point can easily make the eyes tired. Suitable for people who need to alternate between distant, medium, and near vision.

However, with the development of science and technology, more and more progressive multifocal glasses have emerged that have a wider field of view, more comfortable wearing, and better meet the needs of eyes. Nowadays, the use rate of progressive lenses among middle-aged and elderly people abroad is quite high. Single-lens and double-lens reading glasses are gradually being replaced by progressive multifocal glasses.



You need to buy real titanium frames.

In general, titanium frames range from hundreds of yuan to thousands of yuan. Many store counters display frames called pure titanium, but if you look closely at the labels, there is no indication of the titanium content or composition. When you buy titanium frames, check if they are titanium or pure titanium. In reality, pure titanium glasses frame refers to the composition of titanium more than 99%, so you can use the weight to see if it is pure titanium. If the frame is heavy, it is definitely not pure titanium.


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.



Cheap reading glasses can cause eye strain.

The optical quality of cheap reading glasses is often not as good as that of custom glasses for computer use and reading. Moreover, cheap reading glasses often offer no protection against the high-energy blue light emitted from computer screens and other digital devices.


The function of eyeglasses cloth

Under a powerful microscope, the fibers of the cloth are more closely arranged than those of ordinary cloth, and the material itself is softer than ordinary cloth. That's because eyeglasses under the eye are almost always coated, with each standard lens having seven layers of different functions on the front and back surfaces, to extend lens life. It can thoroughly remove the stubborn stains left on the lens to make the picture clear. It can clean all kinds of glass, resin, and other materials of glasses, glass mirrors, and other mirror surfaces, remove stains, and grease absorption.


Sale priceFrom
Sale priceFrom


What Strength Reading Glasses Do I Need?

What strength reading glasses do I need? You can choose the reading glasses strengths by age or you can also perform a reading glasses test. If you are aging from 40 to 44, the +0.75 to +1.00 dioptre power is recommended. If you are aging from 45 to 49, the +1.00 to +1.50 dioptre is recommended. Age from 50-54, recommended power is +1.5 to +2.00 dioptre. Age from 55-59, recommended power is from +1.50 to +2.25 dioptre. Age from 61-65, recommended power is from +2.25 to +2.50 dioptre.

If you find two different strengths of reading glasses are available, choose the lower power because too strong strength can cause discomfort compared to weaker powered glasses and can even lead to nausea and dizziness.

So, if you need a pair of reading glasses, try Koalaeye Optical, which is an online glasses store. It provides all kinds of eyeglasses, sunglasses and frames. You can choose the satisfied one from here.

Leave a comment

All comments are moderated before being published.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.