No line bifocals reading glasses, Pros and cons
The lens looks like a single vision lens and does not see the dividing line of the degree change. Not only is it beautiful, but more importantly it protects the wearer's age privacy (for reading glasses wearers), and there is no need to worry about leaking the age secret by wearing a mirror.
No line bifocals reading glasses (also known as progressive multifocal eyeglasses) are glasses that upper part is used to look far, the middle is used for medium distance and the bottom is used to read.
Pros: The power of no line bifocals lens changes gradually over the progression zone from the distance power at the top to the near power at the bottom, which has many advantages over ordinary lenses. Click for More information.
External progressive lens vs. Inner progressive lens
External Progressive lens is also called the front surface progressive lens, which is to put the function side of the power changing zone on the front surface of the lens, farther away from the eye.
The Inner progressive lens, also known as the posterior surface design progressive lens, we can know from the name, this progressive lens is to put the function side of the power changing area on the back surface, closer to the eye. The Inner progressive lenses have more wild field of view. Pros and Cons.