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Jinghua Chen, Gloria DeWalt, William Eldred, Marcus Gingerich, Douglas Shire, Joseph F Rizzo, Henry J Kaplan; Acute Synaptic and Neuronal Anatomical Changes Following Insertion of Sub-Retinal Electrode Array in an Enucleated Human Eye. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3732. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
This work is related to the efforts of the Boston Retinal Implant Project to develop a sub-retinal prosthesis to restore basic vision following photoreceptor degeneration. A sub-retinal prosthesis was implanted into an enucleated human eye, after pars plana vitrectomy and a focal retinal detachment, to evaluate acute synaptic and neuronal anatomical changes in response to the surgery and implant.
The inactive sub-retinal implant included secondary power and data coils, a hermetic case and a parylene coated polyimide electrode array. A pars plana vitrectomy was performed and a focal retinal detachment was created. The coil and the hermetic case were sutured onto sclera and the electrode array was placed into the sub-retinal space ab externally after enucleation. The array remained in situ for about 30 minutes prior to fixation in paraformaldehyde. The retina close to versus further away from the array were cryoprotected, and embedded before being frozen. Cross sections were obtained. Normal donkey serum was used to minimize non-specific binding prior to incubation in various antisera: calretinin, parvalbumin, and synaptotagmin at 4°C. Following incubation in fluorescently conjugated secondary antibodies slides were coverslipped in Vectashield Antifade Mounting Medium with DAPI. Confocal microscopy was used for visualization.
There was a reduction in calretinin immunoreactivity in the outer plexiform layer, reduced somatic labeling in the inner nuclear layer, and a loss of punctate labeling in the inner plexiform layer near the array compared to further away. Similarly, there was a decrease in parvalbumin labeling in horizontal cell somata in the inner nuclear layer near the array and there were extensive arborizations into the outer and inner nuclear layers compared to regions further away. And, there was a reduction in synaptotagmin positive punctate labeling in both the inner and outer plexiform layers near the array compared to retina further away.
Neuronal and synaptic changes were present near the implant. Additional work will be necessary to determine whether changes are transient or long lasting and to evaluate how these cellular changes may affect vision restoration. These results are of uncertain significance given that this is a singular case and that there was no control eye for comparison. Control studies are underway.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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