Abstract: A multifocal Fresnel lens construction suitable for use in optical systems with multifocal requirements. It is designed as a multifocal zone plate to allow an annular ring construction that isn't width limited by diffraction aberrations. This is accomplished by modifying the phase separating annular rings of a zone plate, with curved or inclined optical facets of varying refractive indices, which can then function as Fresnel rings corresponding to the different focal powers desired.

Abstract: A multifocal lens design suitable for use as an opthalmic contact lens. A zonal bifocal contact lens utilizes the multifocal Fresnel lens designs which have their multifocal property distributed approximately throughout the lens. This is accomplished by a lens construction in which the optical facets are interfaced without any non-refractive ledges or steps occurring between adjacent facets.

Abstract: A multiscale perimeter is a device which has a curved surface for examining the peripheral field of vision, and which has an opening in its central portion to allow view of a surface set at a greater distance from the patient's eye to permit a more magnified examination of the central field of vision.