Optokinetic after nystagmus is affected by many factors. We investigated the changes of OKAN response after repeated optokinetic stimulatin. Normal subjects (n=9) received optokinetic stimulation for 60 seconds (40 deg/sec 5.16 target spacing)
and
then
OKAN was recorded for 20 seconds. The subjects were exposured on optokinectic stimuli three times first day. Time intervals were 1, 2, 5, 7, 14, 21, 28, 35, 42 and 49 days following the last test. Time constant, initial slow phase eye velocity
(2sec)
and numbers of OKAN were evaluated. Time constant and numbers of OKAN have decreased after first exposure of optokinetic stimuli and reduction of OKAN has been maximized after 3 performance of OKAN test. After 28 days following the last test, the
OKAN
response was recovered same as a degree of initial OKAN response. Asymmetry increased by repeated stimulation between 1 day and 7 day but there was no statistical difference.
Maximum decrease of initial slow phase eye velocity was shown after 3 performance of OKAN test but recovery of OKAN response was slow without statistical difference. OKAN was decreased by repeated exposure on optokinetic visual stimuli. The
effects
of
repeated stimulation was disappeared after test interval of 4 weeks or more. (Korean J Otolaryngol 38:4, 1995)
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