97th DOG Annual Meeting 1999

P595

COMBINED ANTERIOR AND POSTERIOR SEGMENT PROCEDURE FOR IMPLANTATION OF A COMPLEX RETINAL PROSTHESIS IN THE RABBIT

M. Vobig, H. Berk, P. Walter and K. Heimann

Retina implants are considered a technological approach for the treatment of certain retinal degenerations and are currently tested in animals. A division of the electronic components is required for intraocular implantation of currently available devices. The receiver is placed in the capsular bag and the stimulator is fixated onto the retinal surface. Both parts of the prosthesis are connected by a flexible microcable.

Methods: Retina implant systems for epiretinal electrical stimulation with telemetric signal- and energy-transfer were implanted in rabbits. Initial cryopexy and rTPA-injection were done in order to obtain a posterior vitreous detachment. Two weeks later extracapsular lens extraction by phakoemulsification and vitrectomy were performed. Three weeks later the prosthesis was implanted after removal of the remaining vitreous. Clinical follow up was performed for up to six months including electrophysiological tests.

Results: The procedure proved to be feasible, a subdivision into multiple steps leads to a minimization of postoperative irritation. Application of modern surgical techniques allows a controlled epiretinal fixation of the retinal stimulator, despite of poor visibility due to the receiver component in the capsular bag. Postoperative complications could be avoided by use of heparin and steroids as additives to the irrigation solution. Clinical follow-up revealed stable conditions.

Discussion: The currently available devices for epiretinal electric stimulation are implantable in principle. A less traumatic approach can only be achieved by futher miniaturization of the electronic components. The prospects for realization and implantability of such a prosthesis continue to be favourable.

University of Cologne, Dept. of Ophthalmology, Joseph-Stelzmann-Str. 9, 50931 Cologne, Germany

founded by BMBF grant IN501 K and Köln Fortune program


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