Abstract

To correct presbyopia with contact lenses, three means exist for a long time: monovision, translating bifocals and simultaneous vision. The main feature of the last one is to produce on the retina, two or more images from a single object, each corresponding to a different optical power. However, only one of these images can be in-focus at one time. The out-of-focus images of an extended object produce a loss of contrast in the in-focus image, with respect to sharp images produced by a spherical lens. So it is necessary to devise specific tools to assess the physical quality of these multifocal contact lenses correcting presbyopia.

© 1991 Optical Society of America