Physiologic Hyperphoria and the Dorsal Light Reflex in Humans with Normal Binocular Vision

Abstract

We read with interest the study by Wang and Bedell (2005) that examined the influence of asymmetrical illumination on physiologic hyperphoria (an ocular movement qualitatively similar to dissociated vertical divergence) in normal humans. Of 30 subjects tested with a Maddox rod to subjectively assess diplopia, eight showed evidence of bilateral hyperphoria of the occluded eye when a dark occluder was used. Interestingly, four of these subjects displayed a physiologic hyperphoria that converted to a hypophoria of the occluded eye when an illuminated occluder was used, consistent with a human dorsal light reflex (Brodsky, 1999). We are concerned that the methodology of this study may have led the authors to the erroneous conclusion that “little or no vestige of the dorsal light reflex occurs in normal individuals.” First, diplopia was used as an endpoint rather than eye position. Physiologic hyperphoria is a tiny response, usually