AbstractSome hypermetropes, when corrected with contact lenses, appear to have a much smaller AC/A ratio than when corrected with spectacle lenses. Ocular convergence measured with contact lenses is greater than that measured with spectacles. Studies were carried out to establish the cause of these effects. Theoretical considerations are compared with the experimental results obtained. This study emphasizes the importance of the different amounts of magnification induced by contact lenses as compared with spectacles.