Bifocal Lenses
These are a two-power lens designed for 2 focus distances . Generally it is for distance/reading use i.e. for that meeting at work, however any focus can be selected. For the computer, depending on the person’s age a middle distance/reading bifocal is often used to prioritise the depth of focus problems associated with different working distance on a desk-computer environment. For some there is a need to have their distance vision clear in the top of the frame, thus the trifocal was invented.
