Vertical End-Point Nystagmus

End-point nystagmus (EPN) is a usual feature of horizontal eccentric gaze but vertical EPN had not been measured. We investigated stability of eccentric gaze in 15 normal subjects (8 men), ages 16-46 (mean 28, SD 8), using a magnetic search coil method with a coil on the dominant eye and the fellow eye occluded. Gaze was recorded in primary position, 40 degrees upward 40 degrees downward, and 45 degrees temporal, under two conditions: 1) fixation of a laser dot target on a featureless screen and 2) in total darkness while subjects attempted to maintain fixation on an imaginary target position. Each trial was recorded for 1 1 minute. We selected an amplitude resolution of 0.2 degrees and measured slow phase (drift) velocities and fast phase amplitude by computer.