http://www.evrs.eu/medias/2006/congress/Chronic-Retinal-Chip-Implant-in-Blind-Patients-with-Retinitis-Pigmentosa.swf

Gisbert Richard, MD (Hamburg, Germany), Michaela Velikay Parel, MD (Graz, Austria), Ralf Hornig, MD (Bonn, Germany), Matthias Feucht, MD (Hamburg, Germany)

PURPOSE:

To evaluate the performance of an investigational Retinal Implant System in blind patients with retinitis pigmentosa. Objectives of the study are also to test the feasibility of the surgical implantation method and the toleration of the implant by the eye over time, to control the wireless signal transmission for both data and energy and to evaluate the optimal stimulus
parameters.

METHODS:

The study is an open, single center, pilot study. It is conducted under the terms and conditions of the Declaration of Helsinki and GCP-guidelines. The Retinal Stimulator is fixated by a tack, which is inserted into the retina at a predefined location. The microcontact film is placed in the macular area and fixed with a silicon retainer ring. The extraocular part of the Retinal Stimulator is fixed onto the sclera. The implant carries 49 stimulation electrodes. The energy for the Retinal Stimulator is provided through a radio frequency transmission loop and the vision data is sent via an optical link, both of which are embedded within a handheld unit.

RESULTS:

At the current time, an implantation has been performed in four subjects. The intraocular fixation (via tack) of the electrode array and the extraocular fixation of the device proved to be surgically feasible. The implants are very well tolerated in the patients’ eyes. No incidence of cell growth has been observed, no irritation has occurred as evidenced by fluorescein angiograms and optical coherence tomography. The fixation with one retina tack enables a close proximity between electrode array and retina. Results from this trial demonstrate the feasibility of a chronic implant system to electrically stimulate the retina for eliciting perceptions resulting from defined input signals. The follow-up period of more than 5 months clearly shows that the implant is well tolerated.

CONCLUSION:

The fixation is stable and no inflammatory reaction or cell proliferation has been observed. The completely wireless data and energy transmission into the implant allow restricted eye movement and is therefore considered suitable as a long-term solution.