Statistical evaluation of nystagmus in cupulometry.

Abstract

The literature on cupulometry shows inconsistent data as to (1) the magnitude of the time constant T1; (2) the inter-individual variation between subjects; (3) the difference between clockwise and counter-clockwise rotation, and (4) the linearity of the system. In our investigations, the nystagmus was measured after a start or a stop in angular velocity. All determinations were carried out six times for 5 subjects. The time constant T1 was calculated from the slope of the decay of the slow-phase eye velocity. Statistical evaluation of the results showed: a test-retest variability which is greater than the inter-individual variability; significant inter-individual differences between subjects; mean values of T1 for clockwise and counter-clockwise rotation of 13.2 (SD 1.4) and 12.8 (S.D. 1.7) sec, respectively; a significant difference of T1 between clockwise and counter-clockwise rotations for individual subjects at the 95% level; no relation between T1 and the amplitude of the step in angular velocity, and a linear increase of the maximum slow-phase eye velocity with the amplitude for velocities below 100 degrees/sec, whereas at higher velocities, saturation occurs.