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.
Rimless Glasses 393014
They are not heavy, with a nose pad and spring hinge. It is a metal alloy frame, and it has a designer acetate temple. This pair of glasses show lens shape #226. These different lens shapes and selection of size can greatly change the overall look and final size.
What Are Transition Lenses?
Transition lenses, also called photochromic glasses are eyeglasses lenses that change their colors with light. The transition lenses darken in the sunlight and lighten in the softer light or the dark. These transition lenses provide the convenience of sunglasses without having to wear them over your prescription glasses and having to constantly switch between the two.
But there are some common transition lenses problems. So, we will list some of them. Are transition lenses worth it? After reading this post, you will find them.
A round face fits on a square frame.
The human face of a round face is shorter. So they had better match the slender frames that take curves slightly to reconcile the whole feeling. Angular and square frames are helpful to modify facial lines (prominent longitudinal lines). This can promote strengths and avoid weaknesses so that your face appears contour.
What are the benefits of pure titanium frames?
This is a kind of metal material with a titanium content of up to 89%, and the most amazing features of this kind of material are the high melting point, and it can withstand high temperatures.Apart from carbon fiber, pure titanium is the lightest material of all.The overall mass is not heavy, so it does not cause pretty large pressure on the bridge.Meanwhile, it has strong corrosion resistance. Pure titanium glasses are designed ergonomically, so there is no need to worry about deformation or fading even if they are used for a long time.So it is loved by many consumers.
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.
The categories of rimless glasses
Rimless glasses can be divided into metal rimless glasses and plastic rimless glasses according to the material. According to the metal category, they can be divided into nickel-copper alloy, memory titanium alloy rimless frames.
According to the elastic order of the frame, the softest and elastic kind is the plastic rimless glasses. The benefits are the lightest weight and the lowest price. The disadvantages are the short service life, faded look after the sun, and single appearance, which are suitable for children or teenagers in the stage of corrective treatment. The second elasticity is the memory titanium alloy rimless frame. They use aviation metal titanium as the raw material, suitable for people with sensitive skin, and have lighter quality, better durability, more styles.
