THRESHOLDS FOR DETECTION OF A TARGET AGAINST A BACKGROUND GRATING SUGGEST VISUAL DYSFUNCTION IN MIGRAINE WITH AURA BUT NOT MIGRAINE WITHOUTAURA

Square-wave gratings with particular spatial characteristics induce vi sual illusions. Patients with migraine are particularly susceptible to these illusions and report discomfort. Their discomfort tends to be g reater when the gratings are illuminated by red light, a tendency not shown by controls. Gratings that induce illusions have been found to i mpair the recognition of optically superimposed targets in headache-fr ee control subjects. We measured the impairment of target detection un der illuminants of various chromaticities in migraineurs with and with out aura and in matched controls. Migraineurs with aura had significan tly higher thresholds for target detection than either migraineurs wit hout aura or controls; in addition, the effect of chromaticity was sli ghtly more pronounced in both migraine groups than in the control grou p. These Findings are consistent with a recent suggestion that migrain e with aura might give rise to subclinical damage to the primary visua l cortex.