BIFOCAL CONTACT LENSES

SEGMENT DESIGNS

Segments can be designed in 
contact lenses similar to 
those in spectacle bifocals.  
In this case the lenses are an 
alternating bifocal.  An 
alternating bifocal is one in 
which the segment (near portion) 
is usually below the pupil with 
distance gaze and with down gaze 
the lens moves up (alternates) so 
the near portion of the lens 
covers the majority of the pupil.

In order to keep the segment in the 
inferior position prism is used to prevent the lens from rotating.