December 2002
Volume 43, Issue 13
Free
ARVO Annual Meeting Abstract  |   December 2002
Functional Deficits in a Rat Model of Chronically Elevated Intraocular Pressure
Author Affiliations & Notes
  • G Ben-Shlomo
    School of Veterinary Medicine Hebrew University of Jerusalem Rehovot Israel
  • S Bakalash
    Department of Neurobiology Weizmann Institute of Science Rehovot Israel
  • GN Lambrou
    Novartis Ophthalmics AG Basel Switzerland
  • CL Percicot
    Novartis Ophthalmics AG Basel Switzerland
  • WW Dawson
    Department of Ophthalmology University of Florida Gainesville FL
  • M Schwartz
    Department of Neurobiology Weizmann Institute of Science Rehovot Israel
  • R Ofri
    School of Veterinary Medicine Hebrew University of Jerusalem Rehovot Israel
  • Footnotes
    Commercial Relationships    G. Ben-Shlomo, Novartis Ophthalmics AG F, R; S. Bakalash, None; G.N. Lambrou, Novartis Ophthalmics AG E; C.L. Percicot, Novartis Ophthalmics AG E; W.W. Dawson, Novartis Ophthalmics AG F; M. Schwartz, Proneuron Biotechnologies C, P; R. Ofri, Novartis Ophthalmics AG F, C, R. Grant Identification: Support: Novartis Ophthalmic AG, Proneuron Biotechnologies and the Glaucoma Research Foundation
Investigative Ophthalmology & Visual Science December 2002, Vol.43, 2142. doi:
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    • Get Citation

      G Ben-Shlomo, S Bakalash, GN Lambrou, CL Percicot, WW Dawson, M Schwartz, R Ofri; Functional Deficits in a Rat Model of Chronically Elevated Intraocular Pressure . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2142.

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Abstract

Abstract: : Purpose:To use the pattern electroretinogram (PERG) to detect retinal function deficits in a rat model of chronically elevated intraocular pressure (IOP). Methods: Argon laser photocoagulation of the episcleral veins and limbal plexus was used to induce unilateral IOP elevation in 6 Lewis rats. Scotopic PERG responses were recorded prior to lasering and 3 weeks later. Stimulus was a series of 5 shifting (6 Hz) checkerboard patterns of decreasing spatial frequency (32-2 cycles per degree, cpd), projected ophthalmoscopically on the animals' fundus. Results: Mean (± standard deviation) IOP was 17.9 ± 4.2 mm Hg in normal eyes, and 30.8 ± 6.0 mm Hg in lasered eyes. Responses from both normotensive and hypertensive eyes showed a typical spatial frequency dependence. N1P1 amplitude increased with the size of the stimulus, peaking in response to a 4 cpd pattern. In eyes with elevated IOP, signal amplitude was reduced in response to all patterns, with significantly (P < 0.05) lower signals recorded in response to wide stimuli. Mean responses to 4 cpd patterns were 12.26 ± 3.59 uV in normal eyes, compared to 6.95 ± 0.76 uV in eyes with elevated IOP. Mean responses to 2 cpd patterns were 7.91 ± 1.97 uV in normal eyes, compared to 5.52 ± 1.61 uV in eyes with elevated IOP. Signal latency was similarly decreased in these eyes. Conclusion: The PERG of rat eyes with chronically elevated IOP shows an amplitude reduction of 30-43% in response to wide gratings. These deficits provide an indication of functional damage in the magnocellular pathways, which have been shown to be preferentially damaged in non-human primate models of glaucoma. The evidence for functional deficits, combined with tonometry and documentation of ganglion cell loss, confirms the validity and importance of this animal model in glaucoma research.

Keywords: 396 electroretinography: non-clinical • 316 animal model • 557 retina: proximal(bipolar, amacrine, and ganglion cells) 
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