SPECTACLE LENSES WHICH CORRECT OBLIQUE ASTIGMATISM AT ALL OCULAR ROTATIONS - INVESTIGATION OF MERTE CONICOIDAL SURFACES

Merte (1950) described lens forms that correct oblique astigmatism at all ocular rotations. The front surfaces of all lenses were flat, and the back surfaces were made aspherical as conicoids. Merte did not pro vide a derivation of his formulae for the appropriate conicoidal surfa ces. We show that Merte's formula is correct and describe the nature o f appropriate conicoidal back surfaces of spectacle lenses. Copyright (C) 1996 The College of Optometrists.