Laboratory evaluation of commercial aspheric aphakic lenses.

Four types of commercial aspheric aphakic lenses were assessed with respect to mass, spectacle magnification, off-axis power errors, and peripheral distortion. The aspheric lenses have better distortion and off-axis imagery properties than spherical flat back lenses, but the improvement in distortion properties is small for those lenses whose design form specifies a flattish back surface. The claims concerning the distortion properties of these lenses are exaggerated. The shape (bending) of lenses has a large effect on spectacle magnification, peripheral distortion, and off-axis imagery.