Retinal image quality with different designs of bifocal contact lens

Abstract The design of alternating andsimultaneous-vision bifocal contact lenses is discussed in relation to the form of the geometrical point images (spot diagrams) that they produce on the retina. Examples are given to show that the effects of variations in lens decentration and in the diameter of the entrance pupil of the eye depend upon the lens design used. An alternative interpretation of imaging performance in terms of the through focus modulation transfer function is briefly outlined.