March 2012
Volume 53, Issue 14
Free
ARVO Annual Meeting Abstract  |   March 2012
Subretinal Implantation Of Photovoltaic Arrays In Rats: In-vivo Imaging And Histological Analysis
Author Affiliations & Notes
  • Yossi Mandel
    Hansen Experimental Physics Laboratory,
    Ophthalmology,
    Stanford University, Stanford, California
  • Moon Kim
    Research R & D Service, Atlanta VA Medical Center, Decatur, Georgia
    Ophthalmology, Emory University, Atlanta, Georgia
  • Alice Adkins
    Research R & D Service, Atlanta VA Medical Center, Decatur, Georgia
  • Daniel Lavinsky
    Ophthalmology,
    Stanford University, Stanford, California
  • Keith Mathieson
    Hansen Experimental Physics Laboratory,
    Stanford University, Stanford, California
  • Philip Huie
    Hansen Experimental Physics Laboratory,
    Ophthalmology,
    Stanford University, Stanford, California
  • Daniel Palanker
    Hansen Experimental Physics Laboratory,
    Ophthalmology,
    Stanford University, Stanford, California
  • Machelle T. Pardue
    Research R & D Service, Atlanta VA Medical Center, Decatur, Georgia
    Ophthalmology, Emory University, Atlanta, Georgia
  • Footnotes
    Commercial Relationships  Yossi Mandel, None; Moon Kim, None; Alice Adkins, None; Daniel Lavinsky, None; Keith Mathieson, None; Philip Huie, None; Daniel Palanker, None; Machelle T. Pardue, None
  • Footnotes
    Support  Dept of Veterans Affairs, Research to Prevent Blindess, P30 EY006360, NIH Grant R01-EY-018608, Air Force Office of Scientific Research Grant FA9550-04, Stanford Bio-X IIP Grant
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 5513. doi:https://doi.org/
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      Yossi Mandel, Moon Kim, Alice Adkins, Daniel Lavinsky, Keith Mathieson, Philip Huie, Daniel Palanker, Machelle T. Pardue; Subretinal Implantation Of Photovoltaic Arrays In Rats: In-vivo Imaging And Histological Analysis. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5513. doi: https://doi.org/.

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

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Abstract

Purpose: : Close proximity between subretinal implant electrodes and bipolar cells is critical for efficient neural stimulation. Retinal inflammation, fibrosis or gliosis can have adverse effects on implant function. We evaluated the tissue response to subretinal implants having pixels separated by gaps of 5 and 10 μm.

Methods: : Silicon photodiode arrays or inactive SU-8 polymer coated with parylene were implanted through a sclerotomy into the subretinal space of wild type, P23H-1 and RCS rat eyes (n=31). Implants measured 0.8 x 1.2mm and 30μm in thickness, with pixel sizes of 60, 120 and 240μm separated by 5 or 10μm wide trenches. Eyes were followed by fundoscopic examination, fluorescein angiography and/or SD-OCT. Histology was performed on a subgroup with polymer implants after 8 weeks.

Results: : With both types of implants and in all three animal models retinas were edematous and showed some detachment over the implant immediately after surgery. OCT imaging revealed resolution of the retinal detachment within 3 weeks of surgery with the retina achieving close and uniform proximity to the upper surface of the array. Some eyes (n= 9) developed retinal thickening above the implant, likely caused by edema, fibrosis and/or vitreous traction. Fluorescein angiography revealed normal retinal vasculature above the device with some cases of vascular loss at the device edges. Histological analysis revealed very close apposition of the inner nuclear layer (INL) to the implant with retinal cells directly contacting the device. Some inner retinal cells migrated through the 10μm trenches into the subretinal space while fewer cells migrated through the 5μm trenches. Fibrotic and/or gliotic reactions formed around a portion of the implant in some retinas positioned close to the retinotomy site.

Conclusions: : Photodiode arrays were easily implanted in the subretinal space of rat eyes, with the inner nuclear layer located in close proximity to the electrodes. Greater migration of inner retinal cells into the subretinal space was observed through 10μm trenches compared to 5 μm trenches. Research is underway to evaluate the electrophysiological response to subretinal photovoltaic stimulation in-vivo, and prevent any fibriotic or gliotic reactions.

Keywords: retina • low vision • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) 
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