Abstract

Spectacles with manually adjustable power are intended for persons who need a single corrective device for all distances. The design of these spectacles employs two lenses for each eye, one lens of positive power and one lens of negative power. When the lenses are in contact or in close proximity their combined power is designed to be zero for an emmetropic eye, or else it is designed to conform to the prescription for distant vision of a myopic or a hyperopic eye. By mechanically adjusting the spacing between the lenses the wearer achieves visual acuity for any distance.

© 1992 Optical Society of America