Tags

Type your tag names separated by a space and hit enter

Long-term histological and electrophysiological results of an inactive epiretinal electrode array implantation in dogs.
Invest Ophthalmol Vis Sci 1999; 40(9):2073-81IO

Abstract

PURPOSE

Short-term pattern electrical stimulation of the retina via multielectrode arrays in humans blind from photoreceptor loss has shown that ambulatory vision and limited character recognition is possible. To develop an implantable retinal prosthesis that would provide useful vision, these results need to be sustained over a prolonged period of retinal electrical stimulation. As a first step toward this goal, the biocompatibility and the feasibility of surgically implanting an electrically inactive electrode array onto the retinal surface was tested.

METHODS

A 5 x 5 electrode array (25 platinum disc-shaped electrodes in a silicone matrix) was implanted onto the retinal surface using retinal tacks in each of the 4 mixed-breed sighted dogs. Color fundus photography, fluorescein angiography, electroretinography, and visual evoked potentials were obtained preoperatively, at 1-week intervals for 2 weeks postoperatively, then at 2-week intervals up to 2 months postoperatively, and thereafter at 1-month intervals. One dog was killed at 2 months after implantation and a second dog after 3 months of implantation. Histologic evaluation of the retinas was performed. The remaining two dogs continue to be followed beyond 6 months after the implantation surgery.

RESULTS

No retinal detachment, infection, or uncontrolled intraocular bleeding occurred in any of the animals. Retinal tacks and the retinal array remained firmly affixed to the retina throughout the follow-up period. Hyperpigmentation of the retinal pigment epithelium was observed only around the site of retinal tack insertion. No fibrous encapsulation of the implant or intraocular inflammation was visible. A- and b-wave amplitudes of the electroretinogram were depressed at the first postoperative week testing but recovered over the ensuing 1 week and were not statistically different from the normal unoperated fellow eye throughout the postoperative period. N1 and P1 wave amplitudes of the visual evoked potentials were not significantly different from the normal fellow eyes at any of the postoperative test intervals. Fluorescein angiography showed that the entire retina including the area under the electrode array remained well perfused. Similarly, histologic evaluation revealed near total preservation of the retina underlying the electrode array.

CONCLUSIONS

Implantation of an electrode array on the epiretinal side (i.e., side closest to the ganglion cell layer) is surgically feasible, with insignificant damage to the underlying retina. The platinum and silicone arrays as well as the metal tacks are biocompatible. With the success of implanting an electrically inactive device onto the retinal surface for prolonged periods, the effects of long-term retinal electrical stimulation are now ready to be tested as the next step toward developing a prototype retinal prosthesis for human use.

Authors+Show Affiliations

Wilmer Ophthalmological Institute, the Johns Hopkins University, School of Medicine, Baltimore, Maryland 21287, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

10440263

Citation

Majji, A B., et al. "Long-term Histological and Electrophysiological Results of an Inactive Epiretinal Electrode Array Implantation in Dogs." Investigative Ophthalmology & Visual Science, vol. 40, no. 9, 1999, pp. 2073-81.
Majji AB, Humayun MS, Weiland JD, et al. Long-term histological and electrophysiological results of an inactive epiretinal electrode array implantation in dogs. Invest Ophthalmol Vis Sci. 1999;40(9):2073-81.
Majji, A. B., Humayun, M. S., Weiland, J. D., Suzuki, S., D'Anna, S. A., & de Juan, E. (1999). Long-term histological and electrophysiological results of an inactive epiretinal electrode array implantation in dogs. Investigative Ophthalmology & Visual Science, 40(9), pp. 2073-81.
Majji AB, et al. Long-term Histological and Electrophysiological Results of an Inactive Epiretinal Electrode Array Implantation in Dogs. Invest Ophthalmol Vis Sci. 1999;40(9):2073-81. PubMed PMID: 10440263.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Long-term histological and electrophysiological results of an inactive epiretinal electrode array implantation in dogs. AU - Majji,A B, AU - Humayun,M S, AU - Weiland,J D, AU - Suzuki,S, AU - D'Anna,S A, AU - de Juan,E,Jr PY - 1999/8/10/pubmed PY - 2001/3/28/medline PY - 1999/8/10/entrez SP - 2073 EP - 81 JF - Investigative ophthalmology & visual science JO - Invest. Ophthalmol. Vis. Sci. VL - 40 IS - 9 N2 - PURPOSE: Short-term pattern electrical stimulation of the retina via multielectrode arrays in humans blind from photoreceptor loss has shown that ambulatory vision and limited character recognition is possible. To develop an implantable retinal prosthesis that would provide useful vision, these results need to be sustained over a prolonged period of retinal electrical stimulation. As a first step toward this goal, the biocompatibility and the feasibility of surgically implanting an electrically inactive electrode array onto the retinal surface was tested. METHODS: A 5 x 5 electrode array (25 platinum disc-shaped electrodes in a silicone matrix) was implanted onto the retinal surface using retinal tacks in each of the 4 mixed-breed sighted dogs. Color fundus photography, fluorescein angiography, electroretinography, and visual evoked potentials were obtained preoperatively, at 1-week intervals for 2 weeks postoperatively, then at 2-week intervals up to 2 months postoperatively, and thereafter at 1-month intervals. One dog was killed at 2 months after implantation and a second dog after 3 months of implantation. Histologic evaluation of the retinas was performed. The remaining two dogs continue to be followed beyond 6 months after the implantation surgery. RESULTS: No retinal detachment, infection, or uncontrolled intraocular bleeding occurred in any of the animals. Retinal tacks and the retinal array remained firmly affixed to the retina throughout the follow-up period. Hyperpigmentation of the retinal pigment epithelium was observed only around the site of retinal tack insertion. No fibrous encapsulation of the implant or intraocular inflammation was visible. A- and b-wave amplitudes of the electroretinogram were depressed at the first postoperative week testing but recovered over the ensuing 1 week and were not statistically different from the normal unoperated fellow eye throughout the postoperative period. N1 and P1 wave amplitudes of the visual evoked potentials were not significantly different from the normal fellow eyes at any of the postoperative test intervals. Fluorescein angiography showed that the entire retina including the area under the electrode array remained well perfused. Similarly, histologic evaluation revealed near total preservation of the retina underlying the electrode array. CONCLUSIONS: Implantation of an electrode array on the epiretinal side (i.e., side closest to the ganglion cell layer) is surgically feasible, with insignificant damage to the underlying retina. The platinum and silicone arrays as well as the metal tacks are biocompatible. With the success of implanting an electrically inactive device onto the retinal surface for prolonged periods, the effects of long-term retinal electrical stimulation are now ready to be tested as the next step toward developing a prototype retinal prosthesis for human use. SN - 0146-0404 UR - https://www.unboundmedicine.com/medline/citation/10440263/Long_term_histological_and_electrophysiological_results_of_an_inactive_epiretinal_electrode_array_implantation_in_dogs_ L2 - http://iovs.arvojournals.org/article.aspx?volume=40&page=2073 DB - PRIME DP - Unbound Medicine ER -