CONTROL OF THE MYOPIC SHIFT IN MODIFIED BADAL OPTOMETER

Refractive error measurements made with the Badal optometer typically register more myopia than is actually present, In this paper we measur ed the influence of the image size on the endpoint of a Badal optomete r's refractive error measurement, The optometer was modified with a ca mera's zoom lens in such a way that the retinal image size could be co ntrolled, It was found that retinal image size is a major factor in co ntrolling the subjective endpoint. When retinal image size is diminish ed rather than increased as the target approaches the subject, as is t he case under normal circumstances, the perceived endpoint more closel y agrees with the actual refractive error. (C) 1998 The College of Opt ometrists. Published by Elsevier Science Ltd.