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T.L. Alvarez, J.L. Semmlow, C. Pedrono; Peak Velocity of Divergence Eye Movements varies as a Function of the Initial Position . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2537.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Divergence eye movements are the outward turnings of the eyes when a person looks from near to far. This study documents the dynamics of these divergence movements to step stimuli revealing unique underlying control characteristics. Methods: Binocular eye movement recordings were obtained from three subjects using an infrared limbus–tracking device. Four degree divergence step stimuli were presented beginning at 5 different initial positions: 20, 18, 16, 12 and 8 degrees convergent. Stimuli were randomly presented after a random delay to avoid prediction. Results:Results show that the mean peak velocities decrease as a function of initial convergence position (see table). Discussion: Results show that the dynamics of divergence eye movements are quite different from those of convergence. While convergence dynamics are more–or–less independent of initial position, divergence dynamics are strongly dependent on the initial position. Movements beginning from positions close to the head are much faster and reach peak velocities nearly double those beginning at more divergent positions. These differences must be associated with motor components (since the stimuli were the same) possibly nonlinearities in the lateral and medial recti muscles. These position dependent dynamics may be related to the strain that some people experience when viewing a near target. Conclusions: Divergence eye movement dynamics are different from convergence dynamics: responses beginning from position near the head are much faster than those of equal size that begin from further away. Acknowledgement: This research was funded from Essilor International. Peak Velocity Mean (deg/sec) and Standard Deviation
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