July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Asymmetry of optokinetic nystagmus in early glaucoma
Author Affiliations & Notes
  • Esther G Gonzalez
    Vision Science, Krembil Research Institute, Toronto, Ontario, Canada
    Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada
  • Graham E Trope
    Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada
  • Saba Samet
    Vision Science, Krembil Research Institute, Toronto, Ontario, Canada
  • Luminita Tarita-Nistor
    Vision Science, Krembil Research Institute, Toronto, Ontario, Canada
  • Footnotes
    Commercial Relationships   Esther Gonzalez, None; Graham Trope, None; Saba Samet, None; Luminita Tarita-Nistor, None
  • Footnotes
    Support  Bright Focus Foundation Grant G2017093
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 1826. doi:
  • Views
  • Share
  • Tools
    • Alerts
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Esther G Gonzalez, Graham E Trope, Saba Samet, Luminita Tarita-Nistor; Asymmetry of optokinetic nystagmus in early glaucoma. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1826.

      Download citation file:

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

  • Supplements

Purpose : In humans with normal stereopsis, nasal and temporalward motion elicit symmetrical horizontal optokinetic nystagmus (OKN), but a preponderance of nasalward OKN is found in very young children and in people with amblyopia. Because glaucoma patients exhibit deficits in stereoscopic vision, we conducted a prospective, observational studyto examine the symmetry of their OKN.

Methods : Twelve patients with a diagnosis of early stage open angle glaucoma (mean age = 65.33 , SD = 12.74) and 12 age-matched controls (mean age = 68.75, SD = 8.40) participated. Patients did not differ from controls in age or functional measures (acuity, stereoscopic thresholds, visual fields), but they had abnormal structural values (retinal nerve fibre layer, cup-to-disc ratio). For the patients, both structure and field functions were the same in the two eyes.
Horizontal “stare” OKN (i.e., with passive, relaxed fixation) was tested with sinusoidal luminance gratings (spatial frequency 0.5 cy/deg) moving to the right and to the left at 3, 12 and 24 deg/s. Participants were tested monocularly (left and right eye) and binocularly in 10 s trials with all three viewing conditions randomized. OKN gain was obtained by dividing the velocity of the mean smooth pursuit component of the OKN by the stimulus velocity, and its naso-temporal asymmetry index (NT) by dividing the difference of the nasal (Ng) and temporal (Tg) gains by their sum: NT = (Ng-Tg)/(Ng+Tg).

Results : The binocular OKN gains of both groups were not different from each other (p = 0.77) and their magnitude decreased as a function of stimulus velocity (p < 0.001). Controls showed no difference between the eyes (p = 0.15) but glaucoma patients did (p = 0.01), showing a positive NT asymmetry for the left eye (mean NT = 0.08; SD = 0.13) and a negative NT asymmetry for the right eye (mean NT = -0.06; SD = 0.11), which is equivalent to a right-to-left (RL) preponderance that has not been reported before. The mean RL preponderance of the patients correlated significantly with their stereo thresholds [r(10) = 0.52, p = 0.04].

Conclusions : This study shows that, in early glaucoma, there is a right-to-left asymmetry in the gain of OKN. This asymmetry may be related to a delay of the input from one eye relative to the other which may alter the binocular interactions in visual cortex.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.


This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.