Foveation dynamics in congenital nystagmus. I: Fixation.

摘要: Congenital nystagmus (CN) has been described as a 'fixation' implying an inability to fixate target. However, each cycle of CN contains target-foveation period during which the eye velocity is at, or near, zero. Prolongation foveation time, reduction retinal image and cycle-to-cycle repeatability all contribute increased visual acuity. We developed several methods accurately measure dynamics in CN; their use illustrated on individual with typical idiopathic no afferent defects. During eight 5-second intervals fixation stationary target, horizontal standard deviation (SD) mean position (FPOS) was 12.82 minarc SD 118.36 minarc/sec. The means total non-foveating peak were 43.17 25.32 respectively. foveation-time interval (eye less than equal 4 degrees/sec) 57.27 msec. FPOS for best 1-second (4 successive cycles), record, 0.71 minarc. Histograms revealed peaks at 0 +/- 10 240 small vertical component (16 peak-to-peak) had 6.56 A function related acuity derived that more sensitive intensity. resulting from convergence base-out prisms due time. Although it might appear defect fixation, this strong reflexes sense he able (within 1 minarc) achieve (interbeat) maintain (intrabeat) target appreciable periods Our data support hypothesis individuals do not have primary disturbance fixation.