The effect of aging on torsional optokinetic nystagmus.
OBJECTIVE
The effect of aging on torsional optokinetic nystagmus (tOKN) is unknown. The authors investigated changes in tOKN associated with aging in a group of healthy subjects.


METHODS
Monocular torsional eye movements were recorded from 30 subjects between 19 and 72 years of age. Constant-velocity rotary stimuli in clockwise and counterclockwise directions were used to elicit tOKN at 40 degrees /s and 400 degrees /s.


RESULTS
The number of subjects in whom tOKN could not be detected increased with age and was consistent in both directions of stimulation and at both angular velocities of stimulation.


CONCLUSIONS
tOKN appears to fail increasingly with age, in contrast to previous reports of horizontal and vertical OKN systems. This indicates that the ability to respond to rotary motion is more sensitive to the effects of aging.
Farooq
Shegufta J
SJ
University of Leicester, Ophthalmology Group, Faculty of Medicine and Biological Sciences, Leicester, UK.
Gottlob
Irene
I
Benskin
Sherwin
S
Proudlock
Frank A
FA
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017120:Nystagmus, Optokinetic / Q000502:physiology*; D054159:Torsion, Mechanical