March 2012
Volume 53, Issue 14
Free
ARVO Annual Meeting Abstract  |   March 2012
Changes in Electrophysiology & Retinal Ganglion Cell Number in a Magnetic Bead-injection Rat Model of Experimental Glaucoma
Author Affiliations & Notes
  • Sauparnika Vijay
    Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, United Kingdom
    NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital & UCL Institute of Ophthalmology, London, United Kingdom
  • Annegret Dahlmann-Noor
    Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, United Kingdom
    NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital & UCL Institute of Ophthalmology, London, United Kingdom
  • Silke Becker
    Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, United Kingdom
  • Hari Jayaram
    Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, United Kingdom
    NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital & UCL Institute of Ophthalmology, London, United Kingdom
  • Ashkan Khalili
    Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, United Kingdom
    NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital & UCL Institute of Ophthalmology, London, United Kingdom
  • G Astrid Limb
    Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, United Kingdom
    NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital & UCL Institute of Ophthalmology, London, United Kingdom
  • Peng T. Khaw
    Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, United Kingdom
    NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital & UCL Institute of Ophthalmology, London, United Kingdom
  • Footnotes
    Commercial Relationships  Sauparnika Vijay, None; Annegret Dahlmann-Noor, None; Silke Becker, None; Hari Jayaram, None; Ashkan Khalili, None; G Astrid Limb, None; Peng T. Khaw, None
  • Footnotes
    Support  Fight for Sight, NIHR Biomedical Research Centre, Helen Hamlyn Trust, Ilse and Michael Katz Foundation
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 170. doi:
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      Sauparnika Vijay, Annegret Dahlmann-Noor, Silke Becker, Hari Jayaram, Ashkan Khalili, G Astrid Limb, Peng T. Khaw; Changes in Electrophysiology & Retinal Ganglion Cell Number in a Magnetic Bead-injection Rat Model of Experimental Glaucoma. Invest. Ophthalmol. Vis. Sci. 2012;53(14):170.

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

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Abstract
 
Purpose:
 

To compare early and late functional changes in retinal ganglion cells in the recently described magnetic bead-injection model of experimental glaucoma in rats.

 
Methods:
 

Three groups of anterior chamber (AC) injections in rat eyes: (1) paramagnetic microbeads, directed into the iridocorneal angle (ICA) using a ring magnet place around the eye (n=10), (2) paramagnetic beads distributed at random, no magnet (n=9), (3) controls: balanced salt solution (BSS) (n=8).Outcomes: (1) full field flash ERG, recorded in both eyes simultaneously: quantification of the amplitude of positive and negative scotopic threshold response (STR), a and b waves; (2) retinal wholemounts: retinal ganglion cells (RGC) count.Prism, GraphPad Software, Inc., was used to perform one-way analysis of variance. The different groups were compared by applying Bonferroni’s correction.

 
Results:
 

At seven days after the injections, the eyes with beads directed to the ICA had a significant reduction of the pSTR when compared to BSS injected eyes, p<0.0001. Eyes with randomly distributed beads also had a reduction in the pSTR when compared to BSS injected eyes, p=0.04. There was no significant difference in the amplitude of pSTR nor nSTR between random bead eyes and eyes with beads in the ICA. There was no significant reduction in the number of RGC across the different groups.Re-analysed based on IOP rise, pSTR amplitude in eyes with high IOP was significantly lower than in eyes with minimal IOP rise.At 28 days after injection, bead-injected eyes had a significant reduction of pSTR compared to BSS injected eyes, p<0.0001. RGC count in the bead-injected groups was significantly reduced compared to BSS injected eyes.

 
Conclusions:
 

In the magnetic bead injection model of rat glaucoma, the IOP rise attenuates RGC function in the retina. Changes in electrophysiology precede changes in retinal ganglion cell number. Specific changes to RGC function might be restricted to the eyes with mild to moderate IOP rise. Figure 1 At seven days after the injections, the pSTR of the eyes with beads directed to the iridocorneal angle with a magnet was significantly smaller than that of the BSS injected eyes . 

 
Keywords: ganglion cells • electrophysiology: non-clinical • intraocular pressure 
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