End-point nystagmus.
Infrared oculography was performed during sustained lateral gaze in 12 normal subjects to investigate end-point nystagmus while fixating a target light. Five failed to develop nystagmus despite deviation up to 40 degrees from 4 to 5 min. Six subjects developed nystagmus immediately or shortly after reaching the deviated position. In one, the nystagmus (0.5 degrees to 1 degree and 1.0 Hz) began with only a 20 degree deviation. In another subject, "fatigue" nystagmus developed after 1 min at 30 degrees, and at 35 degrees nystagmus began within 2 sec. One subject developed only fatigue nystagmus, which began after more than 4 min of sustained deviation. In all instances the slow phase had primarily a linear, rather than exponential, waveform.
D000328:Adult; D004585:Electrooculography; D005133:Eye Movements; D005221:Fatigue / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology