What are bifocals?
A bifocal lens is a lens with two focal points. Because of the imaging principle of the lens, even half of the lens can still present a complete image, and the two images do not interfere with each other. In the past, both short-sighted glasses and presbyopia glasses were called single-focal lenses, which had only one focus. Later it developed to the bifocal lens, and the same lens is divided into upper and lower two parts. The upper part of that lens is used when seeing far, and you look down when seeing close objects, just the reading distance, naturally used the second half.
Best Frames For Heart-Shaped Faces
The heart-shaped face should be one of the favorite faces of Asians. It is characterized by a wide forehead, prominent cheekbones, and narrow and pointed lower jaw. This face shape is not balanced up and down in appearance, and the upper part is larger and more prominent than the lower part. Need to wear sunglasses with a wider bottom, which can increase the width of the lower half of the face. The lower mirror foot position also helps to improve this effect. Don't pick a special big style, normal size will do. Pilot sunglasses with a more angular top and bottom can be used to balance the roundness of the heart-shaped face and chin, increase the sense of facial lines, and visually make the face fuller. Retro black round sunglasses, coupled with a handsome choker, highlight the full street casual style. The recently popular 'inverted triangle sunglasses' are also very suitable for heart-shaped faces. The raised angle of the frame can correct the facial lines and add some angularity to the face. The inverted triangle sunglasses also have a retro temperament, and it feels that there is a mysterious demeanor hidden.
Types of aspheric lenses
There are two types of aspheric lenses: single aspheric surface (single aspheric surface for short, different from the outer aspheric surface and inner aspheric surface) and double aspheric surface (double aspheric surface for short). For the outer aspheric surface, convex is an aspheric surface and concave is a spherical surface. For the inner aspheric surface, a convex surface is a sphere, and a concave surface is an aspheric surface. In addition to correcting aberrations, the double aspheric lens also improves the effective field of vision compared to the single aspheric surface. When people's eyes look through the edge of the lens to see things, like driving when looking at the reflective mirror, it often affects vision because of the large aberration at the edge of the lens. Previous designs of aspheric plates have analyzed a single ray of light passing through the center of the pupil. Wavefront technology controls the entire beam of light passing through the pupil, eliminating high-order aberrations.
What is blue light?
Our daily lives are inseparable from mobile phones, computers, tablet computers, and other electronic products. Many people's eyesight is also going downhill due to long-term exposure to strong light electronic screens, and their eyes are more or less potentially adversely affected. It is found that many optical stores sell blue light filter glasses, which have the function of blocking 99.9% UV and scattered blue light, alleviating visual fatigue. They claim that these glasses can block short-wave blue light emitted by electronic products such as mobile phones and computers, and even prevent age-related macular degeneration so they are much sought after by consumers. The price of these so-called anti-blue-light glasses varies greatly, ranging from dozens of dollars to several thousand dollars. Do these blue light blocking glasses really have so many magical functions?
The natural light seen by the human eye is composed of a spectrum of different colors, including red light, orange light, yellow light, green light, blue light, indigo light, purple light, which gives people a visual feeling of white. Different wavelengths present different colors visually, and the shorter the wavelength, the higher the energy. At present, products with electronic screens such as computers and mobile phones use LEDs and other materials to emit light mainly in three colors of red, green, and blue, and blue light accounts for the main part. Blue light belongs to the range of visible light, belongs to short waves. And the wavelength is between 400 nanometers and 500 nanometers, which is close to ultraviolet and carries a large amount of energy. And this part from 400 nanometers to 450 nanometers is called high-energy short-wave blue light.
How to Choose Reading Glasses?
In this section, we will show you some tips for choosing reading glasses.
Find the right power. When choosing reading glasses, finding the right power would be the most important thing. All reading glasses will have signs or stickers indicating their power. In most cases, they will range from +1 to +4 diopter, in increments of +0.25. So, when choosing reading glasses, try the lowest power first.
Test-drive the glasses. If you have brought reading material with you, try reading it at a comfortable length. If you hold the material too far out to be able to read it, you should increase the power. Keep testing the differences powers until can read clearly at the distance that’s more comfortable for you.
Choose big frames the first time. When choosing reading glasses, you can choose the big frames for the first time. You may need larger glasses frames or lenses to really get the sweet spot of where the prescription is.
And if you have never worn glasses for eye conditions such as nearsightedness, farsightedness or astigmatism, it is likely you will be able to see well with non-prescription reading glasses. So, you can buy these non-prescription reading glasses.
What Do Pinhole Glasses Do?
Pinhole glasses are often used by eye doctors who use them as a diagnostic tool to quickly check for vision impairments. Of course, pinhole glasses are sometimes used to treat nearsightedness or astigmatism. Pinhole glasses are also used in conjunction with an occluder, an instrument used to cover one of your eyes while you read an eye chart. The occluder is solid, while the pinhole glasses have a number of tiny pinholes. So, the doctor often uses it to check the potential of your vision.
Pinhole glasses are often used to check corneal distortion and cataracts. A cataract evaluation includes focusing light in the eye to check if vision capability behind the cataract makes it worth performing surgery.
Why Wear Horn Rimmed Glasses?
Horn rimmed glasses enable you to show off your sophisticated, intellectual side in style. Among the most popular variations, horn rimmed glasses are thicker with black rimmed frames. And this retro eyewear style has been popular for a long time.
So, not only can the horn rimmed glasses can correct your vision problem, but also can make you look more fashionable.