Details

Autor(en) / Beteiligte

• Suzuki, Yasuo
• Shinmei, Yasuhiro
• Nara, Hiroyuki
• Ifukube, Tohru

Titel

Effects of a Fixation Target on Torsional Optokinetic Nystagmus

Ist Teil von

• Investigative ophthalmology & visual science, 2000-09, Vol.41 (10), p.2954-2959

Ort / Verlag

Rockville, MD: ARVO

Erscheinungsjahr

2000

Quelle

MEDLINE

Beschreibungen/Notizen

• To investigate the effects of an imaginary and a visual target on torsional optokinetic nystagmus (tOKN) and directional symmetry of tOKN. Torsional OKN was induced by a rotating random dot pattern (52 degrees in diameter, constant angular velocity: +/-30 deg/sec to +/-52 deg/sec) with an imaginary or a visual target in 11 eyes of 10 healthy humans by dual-search coil methods. Intorsional OKN and extorsional OKN were symmetrical in their slow-phase gain. The mean slow-phase gain (0. 037/0.041, intorsion/extorsion) of tOKN during fixation on a visual target at the center of the rotating random dot pattern was significantly (P: < 0.002) smaller than that (0.051/0.052, intorsion/extorsion) during fixation on an imaginary target at the center of the rotating random dot pattern. The mean tOKN slow-phase beat duration (840 msec/724 msec, intorsion/extorsion) during fixation on the visual target was significantly (P: < 0.002) longer than that (585 msec/543 msec, intorsion/extorsion) during fixation on the imaginary target. In seven eyes of six subjects, the mean slow-phase gain and beat duration (0.034 and 812 msec) of tOKN during fixation on a visual target 6.5 degrees left or right from the center of the rotating random dot pattern were not significantly different from those (0.037 and 825 msec) with a visual target at the center of the rotating random dot pattern (P: > 0.3). A visual target spot suppresses tOKN by a nonpursuit visual system. Intorsional and extorsional OKNs were symmetrical.