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Helmut G. Sachs, Karl Ulrich Bartz-Schmidt, Florian Gekeler, Dorothea Besch, Ursula T. Brunner, Barbara Wilhelm, Walter Wrobel, Veit-Peter Gabel, Eberhart Zrenner; Subretinal Active Electric Implants In Blind Patients. Transchoroidal Surgery - First Surgical Implant Exchange. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4930.
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We demonstrated the save implantation of a subretinal active electric implant via a transchoroidal access and the promising visual results over the past years. Due to protocol the implants were removed in 10 of 11 cases in the first case series. In the new clinical trial the implants are regarded as permanent. Therefore not only a safe explantation but a safe reimplantation is desirable to acheive the benefits of technical improvements. Implant failiure in one case lead to this first ever demonstrated exchange of a transchoroidal implanted structure in humans.
Transchoroidal implanted subretinal stimulation chips with 1500 electrodes on a polyimide film can be explanted without performing intraocular surgery. With a modification of this procedure by using the already implanted device as a guide the reimplantation of a corresponding structure is carried out without performing a vitrectomy. Opening of the globe is not required. Silicone oil is not removed. After reimplanting a new structure via the pre-existing scleral access the old implant can easily be removed. Due to implant failure this new procedure was applied to one of our patients.
The surgical exchange of a transchoroidal placed subretinal implant was performed successfully for the first time ever to our best knowledge. The exchange procedure is far easier than the initial implantation process. The use of the primary implanted device as a guide is mandatory. The substitute could be placed exactly in the same position. No adverse reaction occurred.
The transchoroidal subretinal implantation procedure offers a unique and save access to the subretinal space. Technical progress in electronics or implant malfunction may create the wish to exchange these devices. The described procedure is regarded as proof of principle and offers the chance to have access to the device without the surgical limitations of an extensive 2nd implantation procedure. Thus patients implanted in this early stage of the trial have the perspective to benefit from further developments.
Clinical Trial: :
http://www.clinicaltrials.gov NTC 01024803
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