This study tests the hypothesis that abnormal motion displacement thresholds coexist with scotomas on a finer spatial scale than is measurable by conventional Humphrey perimetry. Eighteen patients with primary open angle glaucoma in one eye, and 18 age matched normal controls underwent motion displacement threshold testing and high spatial resolution perimetry. The motion displacement thresholds were significantly elevated in the glaucoma eyes, in 73% this exceeded normal limits. Ten glaucoma eyes had normal Humphrey 24-2 field nearest the motion test site: of these seven had abnormally elevated motion displacement thresholds and six had fine scale threshold depressions detected with high spatial resolution perimetry. This result suggests that glaucomatous elevations of motion displacement threshold may be present in areas of normal Humphrey 24-2 field, and this may coexist with measurable scotomas beyond the resolution of conventional Humphrey perimetry in some, but not all patients.