Mapping of ophthalmic lens distortions with a pinhole camera

Ophthalmic lenses are produced in a variety of forms each having unique effects upon visual space. The foundation for evaluating visual space distortion associated with ophthalmic lenses is an understanding of the optical input to the visual system. We developed a photographic technique to evaluate the effects of ophthalmic lenses on optical imagery. This technique uses a pinhole camera and an associated lens holder to simulate the eye-lens relation and provide an eye-referenced view of optical space. A rectilinear grid was photographed through Varilux progressive addition lenses (PAL's) and with no lenses in place. Comparison of these photographs provides a measure of relative optical space distortion that should closely approximate relative visual distortion under similar viewing conditions. Our technique provides an optical baseline with which more in depth studies of space perception and adaptation may be compared.