What are bifocal reading glasses and how they work?

[Mableton]

Can anyone here tell me more about bifocal reading glasses? What advantages do they have? Thx very much!!!!!!!!!!!!

[Mabscott]

bifocal is meant for embedding two distinctive optical powers into one single lens, hence the dual near vision correction and distance one. When you want to descry the objects in the far distance, you can focus your eyes upon the upper part of lenses, aiming directly at your myopia. And vice versa, the presbyopia problem will be duly resolved if you shift your focus to the bottom part. In the light of bifocal reading glasses, they do an excellent job in dealing with the shift focus from reading difficulty to viewing inconsistency.

[Mabton]

Bifocal reading glasses offers the magnification at the bottom of the lens, and the top of the lens is just clear glass. when you look down to read, everything is magnified, but when you look up across a room, there is no change.

[MacArthur]

Bifocal reading glasses provide the dual correction for near vision and distance vision