What are the different types of bifocal glasses?

bifocal glasses have taken a long way since Benjamin Franklin in 1784. The glasses were originally created to help people who had problems with how far and close. Rather than a switch between two pairs of glasses, Franklin invented a way to leave both lenses to one frame. Today, many different types of bifocal glasses are available. Surrounding lenses, segmented bifocals and mixed lenses - also called trouble -free or invisible bifocals - are three main types of bifocal glasses.

The same dividing bifocal glasses have lenses cut in two different halves, while the magnifying part on the lower half and a long -distance lens on the upper half. The initial version of the lenses of the same divisions, called a powerful cut, had a visible horizontal line directly through the lens. A powerful cut is the lens, which is most similar to the original Franklin bifocal glasses.

Ultex is another version of Equal Division bifocal glasses. Separation in Ultex lens is marked with line -shaped lineRu's feet, which creates a wide round segment on the lower half of the lens. Between two types of lenses of the same division, Ultex offers more peripheral vision than a powerful cut.

segmented bifocal glasses have only one segment of the lens dedicated to magnification, which is fused into the main lens. Segments can come in many shapes such as a rectangle, circle or shape D, which looks like the main letter D on its side, with a letter curve along the bottom of the lens. The D-SEGMENT is the most popular of segmented bifocal glasses because it is the easiest to adapt to the eye.

mixed lenses are also called non-line bifocals or progressive lenses. The lens hides a line showing the division between the two lenses. Rather than having two different lenses comfortably, the whole lens is a gradient of the increasing force of the lens. The power of full force or reading strength is at the bottom of the lens. Gradient allows the experience of fluid tracking without o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o oBraz's jumps caused by noticeable lines in other types of bifocal glasses, but the gradient in strength can lead to a distorted perspective that can be unacceptable to some.