What kind of glasses are bifocals?
Bifocals are mainly used in presbyopia correction, providing presbyopic opticians with a clear vision for both near and far use in one pair of glasses. The bifocal lens can be divided into two separate areas, with the upper part of the lens providing clear distance vision and the lower part providing clear near vision. The two regions of the bifocal lens provide different refractive forces, and the difference between these two refractive forces is the reading proximal addition, which compensates for adjustment during presbyopic reading.
There are many types of bifocals.
According to the manufacturing means, bifocals can be divided into separate bifocals, gluing bifocals, fusion bifocals, E-type bifocals, or one-line bifocals. The separation one is a simple type of bifocal lens. Two lenses of different strength were used to make it be in the center of the distal and proximal vision areas.
Compared with single vision glasses, bifocals are multi-focal glasses.
Compared with single vision glasses, bifocal glasses, trifocal glasses belong to multi-focus glasses, and the types of trifocal glasses are diverse. When choosing the optical properties of a trifocal lens, it can be thought that the lens is made up of three different lenses: the main lens, the distal optic regions, two appendages. One for the distance and one for the proximal area.
Progressive multifocal glasses are more powerful.
On the premise of the dual vision correction effect, the progressive lens has more stable and complete functions. They provide lasting clear vision. Because the added value is continuously and slowly increased in the related area, the wearer can get a lasting clear vision from the far place to the near place through the progressive glasses. The appearance is better than that of bifocal and trifocal lenses, and there is no subplate dividing line.