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R. Bitra, V. Punia, M. L. Rosenberg; The Incidence and Etiology of Pendular Oscillations in Normal Subjects. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5481.
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To evaluate the incidence of pendular oscillations during fixation in primary position and with eccentric gaze.
We studied horizontal eye position recorded binocularly at 240 hz. using infrared video-oculography. Six normal subjects were asked to fixate a small target at a distance of 70 cm for 40 seconds. Additional targets were spaced at 10° gaze angle intervals from the center (0°) on either side up to 50° at the eye level of the subjects. Each trial consisted of recording the eye movements with the subjects fixating at the center (0°) for a duration of 40 sec, then fixating at each eccentric gaze position to the right for 40 seconds each. This was repeated for leftward excursions. The binocular tracings were evaluated for pendular movements with consecutive slow phases in different directions without intervening saccades. Such movements were than identified as being secondary to a vergence or a versional movement.
All subjects had intermittent pendular wave forms with consecutive slow phases in alternating directions without intervening saccades. At times these were linear and at others more clearly sinusoidal. The amplitudes were generally small (0.02-0.4 deg). They would often consist of a half sinusoidal cycle and at other times a series of several full cycles. In all trials pendular vergence movements were less frequent than pendular versional movements. Although it was variable, overall pendular vergence movements were more frequent in primary position than at eccentric gaze.
Sinusoidal oscillations have been reported to occur in normal subjects at baseline which continue at eccentric gazes but the etiology has not been investigated. Our study shows that pendular movements are common at all positions. Most of the pendular movements are versional while many are also generated by vergence movements. More work must be done to further evaluate the etiology and significance of these movements.
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