BLOC 5: MULTIFOCAL LENSES Subject 16.- Multifocal lenses. Classification. Subject 17.- Bifocal lenses. Subject 18.- Progressive addition lenses.

Subject 16: Multifocal Lenses. Classification. Definition Bifocal Lenses Differences between bifocal lenses and progressive addition lenses Important parameters in multifocal lenses

Definition of Multifocal Lenses Multifocal lenses allow for clear vision at close distances for patients with Presbyopia, where the powers needed for near and far vision (and intermediate vision) are simultaneously incorporated into the lens.

Bifocal Lenses FUSED BIFOCALS

Differences between bifocal lenses and progressive addition lenses PROGRESSIVES DON’T HAVE A SEGMENT (more esthetic) PROGRESSIVES ARE CLEAR FOR ALL DISTANCES PROGRESSIVES HAVE LATERAL ABERRATIONS

Important parameters of multifocal lenses The same as in monofocals f.e.c. for far and f.e.c. for near ADDITION : SUM OF SPHERICAL POWER IN NEAR VISION TO THE SPHERE IN FAR VISION