May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Damage to Eye Movement Center Neurons of the Superior Colliculus in Experimental Primate Glaucoma
Author Affiliations & Notes
  • L. Alarcon-Martinez
    Ophthalmology & Vision Sciences, Laboratory Medicine & Pathobiology, Ophthalmic Pathology Laboratory, University of Toronto, Toronto, Ontario, Canada
    Ophthalmology, University of Murcia, Murcia, Spain
  • N. Gupta
    Ophthalmology & Vision Sciences, Laboratory Medicine & Pathobiology, Ophthalmic Pathology Laboratory, University of Toronto, Toronto, Ontario, Canada
    Keenan Research Centre at the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
  • R. Weinreb
    Hamilton Glaucoma Center, University of California, San Diego, California
  • P. Kaufman
    Ophthalmology & Visual Sciences, University of Wisconsin, Madison, Wisconsin
  • M. Vidal-Sanz
    Ophthalmology, University of Murcia, Murcia, Spain
  • Y. Yucel
    Ophthalmology & Vision Sciences, Laboratory Medicine & Pathobiology, Ophthalmic Pathology Laboratory, University of Toronto, Toronto, Ontario, Canada
    Keenan Research Centre at the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
  • Footnotes
    Commercial Relationships  L. Alarcon-Martinez, None; N. Gupta, None; R. Weinreb, None; P. Kaufman, None; M. Vidal-Sanz, None; Y. Yucel, None.
  • Footnotes
    Support  Glaucoma Research Society of Canada (NG,YY), Institute of Medical Science Undergraduate Research Program, University of Toronto(LM), NIH/NEI (EY02698;PLK), Research to Prevent Blindness, OPREF (PLK)
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 3662. doi:https://doi.org/
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    • Get Citation

      L. Alarcon-Martinez, N. Gupta, R. Weinreb, P. Kaufman, M. Vidal-Sanz, Y. Yucel; Damage to Eye Movement Center Neurons of the Superior Colliculus in Experimental Primate Glaucoma. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3662. doi: https://doi.org/.

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

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Abstract

Purpose: : To investigate whether superior colliculus neurons of the brain are damaged in experimental primate glaucoma by evaluating their pre-synaptic input and post-synaptic dendrites.

Methods: : Macaque monkeys with unilateral experimental glaucoma (n=6) were compared to normal controls (n=7). Optic nerve fibre loss in glaucoma ranged from 29% to 100%. Superior colliculus specimens were cryoprotected, frozen and cut. Sections were double-labelled for vesicular glutamate transporter 2 (VGluT-2; Synaptic Systems), a marker for pre-synaptic glutamatergic RGC terminals, and microtubule-associated protein-2 (MAP-2; Sigma), a dendrite marker. Using confocal laser microscopy, images were captured in a masked fashion, and percent supra-threshold area was measured as an index of immunofluorescence intensity (Image J software, NIH). The glaucoma group was compared to the control group using a t-test.

Results: : In the glaucoma group, mean axon loss was 44.0±43.4%. VGluT-2 intensity index in the superior colliculus was significantly reduced in glaucoma compared to controls (0.011±0.003% vs. 6.359±1.657%, mean ±SEM; p< 0.05). MAP-2 intensity index was also significantly reduced in glaucoma compared to controls (0.239±0.153% vs 1.659±0.443%; p<0.05).

Conclusions: : Reduced glutamate transporter was observed where RGCs terminate on the superior colliculus. Disrupted MAP-2 protein in superior colliculus neuron dendrites were also observed in experimental primate glaucoma. These major neurochemical changes in pre- and post-synaptic elements of the superior colliculus responsible for saccadic eye movements, point to possible eye movement deficits in patients with glaucoma.

Keywords: intraocular pressure • ganglion cells • superior colliculus/optic tectum 
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