April 2010
Volume 51, Issue 13
ARVO Annual Meeting Abstract  |   April 2010
The Spontaneous Vertical Movements Seen During Fixation Are Chaotic
Author Affiliations & Notes
  • M. L. Rosenberg
    Neurology, New Jersey Neuroscience Institute, Edison, New Jersey
  • V. Punia
    Neurology, New Jersey Neuroscience Institute, Edison, New Jersey
  • R. Bitra
    Neurology, New Jersey Neuroscience Institute, Edison, New Jersey
  • M. Kroll
    Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts
  • Footnotes
    Commercial Relationships  M.L. Rosenberg, None; V. Punia, None; R. Bitra, None; M. Kroll, None.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 2538. doi:
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    • Get Citation

      M. L. Rosenberg, V. Punia, R. Bitra, M. Kroll; The Spontaneous Vertical Movements Seen During Fixation Are Chaotic. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2538.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : To better understand the physiology underlying the spontaneous vertical eye movements seen during fixation.

Methods: : We studied binocularly recorded eye movements and pupil size in six normal volunteers at 240 Hz using ISCAN ETL-500 Infrared Video graphic Binocular Recording system (Iscan, Inc., Burlington, Massachusetts). Subjects were instructed to fixate a point presented in the primary position for 40 seconds. A fake eye was recorded under 4 different conditions: once while being held up with one hand, once held with two hands, once on a table and once on the floor to simulate different degrees of movement. Blinks were removed. A 7 column time shifted matrix (A) was generated for each data set using a time delay of 25 seconds between each column and a singular value decomposition was performed. The singular values (S) from the fake eye were compared to those of the subjects’datasets. A state portrait using the first two vectors of the transformed matrix was plotted for each subject and for each tracing done on the fake eye.

Results: : Plots of eye movements vs. time for subjects demonstrate non-periodic waves (oscillations) while plots of the fake eye had the appearance of noise. The normalized mean singular values from the S matrix for the fake eye averaged [1.0000, 0.0012, 0.0011, 0.0006, 0.0005, 0.0005, 0.0004]. Only the first singular value differs from the others (p<0.05). The normalized mean singular values for the subjects averaged [1.0000, 0.3312, 0.2188, 0.1588, 0.1292, 0.1157, 0.1108]. The first three singular values differ significantly from each other and the rest of the values by Student’s t-test (p<0.05). A phase portrait of the first vs. second vector from the transformed matrix of all subjects showed an attractor with a complex pretzel shape. A similar plot from the fake eye trials formed a tight ball with no consistent pattern.

Conclusions: : The uniqueness of the first three vectors of the subject group supports the hypothesis that the waves of eye movements vs. time originate from a nonlinear deterministic dynamic system. The non-repeating pattern of the attractor suggests that this dynamic system may be chaotic. These results indicate that proper modeling of the system requires a multivariable nonlinear system of differential equations.

Keywords: pupil • eye movements • ocular motor control 

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