Eccentric fixation with macular scotoma

摘要: People with macular scotoma tend to read and visually scan more slowly than others equivalently reduced visual acuity but intact central fields. We measured fixation eye movements considered the contribution of variability centripetal drift poor performance. These factors might confound efforts consistently use an optimum retinal locus outside macula. monocular horizontal vertical using a search coil eyetracker while subjects naturally occurring scotomata or control simulated eccentrically fixated single character that was sized their acuity. Motivated long-standing stable maculopathies were chosen estimate attainable performance limits. During attempts fixate, ubiquitous foveal pursuit tendency not found; rather pattern idiosyncratic from subject subject. This finding confirmed by analysis 32 eyes bilateral scotomata. Moreover, speeds (15-200 minarc/sec) too low be functional significance. Drift during eccentric visible target significantly different those after extinguished; however, greater fixation. suggests fovea has specialized slow movements. Fixation increased size for both real scotomata, abrupt rise when diameters exceeded 20 degrees C. A significant minority (39%) adopted two distinct preferred loci (PRL) Multiple PRL also likely if Reasonably steady is thus sizes are smaller approximately