Visual remapping in infantile nystagmus

The possibility that patients with idiopathic infantile nystagmus achieve spatial constancy by visual remapping was investigated by comparing subjective localization of flashed test targets to their absolute position in space and to their absolute position on the retina. Nystagmats first viewed a screen-stationary reference target that was followed by a test flash. A computer used eye movement feedback to precisely control the test flash position on the retina. All six nystagmats detected test flashes throughout their nystagmus cycle. For three nystagmats test flashes (total N = 48) were delivered to the same retinal locus that were, at different times, to the right and left of the reference target. More than two-thirds of such crossover stimuli were correctly located in space: when only those stimuli at least 0.5 deg from the reference were considered, two of three subjects correctly located all stimuli. Taken together these results argue that our subjects could see throughout the nystagmus cycle and shifted their visual map in synchrony with their nystagmus as an explicit means of avoiding oscillopsia.