Bifocals have an additional power on the bottom part of the lens to aid close focus in presbyopic people so they can see far and close with one lens Some people who are young can see far away and close with one prescription, then as they age, it becomes necessary to have an addition in power in the bottom of the lens. A blended bifocal is not a multifocal or progressive lens . Multifocal lenses Like bifocal lenses, multifocal lenses are used primarily to help Presbyopic people focus at distance and near with one lens. Multifocal lenses come in many designs and styles. Multifocal measurement and pupillary distance - measurements for multifocal lenses must be taken by a trained professional.
Improper measurements taken for multifocal lenses are the most frequent reason for non-adaptation.
Frame measurement - frame measurements are sent into the laboratory properly and frames are adjusted properly on patients face before marking optical centers of lenses. Patient motivation - often patient motivation is the determining factor in adaptation to these lenses. If you take the time and wear the lenses regularly without switching to an old pair or giving up, you can adjust. Because the power in a progressive multifocal lens can be adjusted over time, just like a bifocal lens. A multifocal lens gradually changes curvature, thus power As you go towards the bottom of the lens.