New epiretinal implant with integrated sensor chips for optical capturing shows a good biocompatibility profile in vitro and in vivo

BioMedical Engineering OnLine, vol. 20, pp. 102

Abstract

BACKGROUND: Retinal degenerative diseases, e.g., retinitis pigmentosa, cause a severe decline of the visual function up to blindness. Treatment still remains difficult; however, implantation of retinal prostheses can help restoring vision. In this study, the biocompatibility and surgical feasibility of a newly developed epiretinal stimulator (OPTO-EPIRET) was investigated. The previously developed implant was extended by an integrated circuit-based optical capturing, which will enable the immediate conversion of the visual field into stimulation patterns to stimulate retinal ganglion cells. RESULTS: The biocompatibility of the OPTO-EPIRET was investigated in vitro using the two different cell lines L-929 and R28. Direct and indirect contact were analyzed in terms of cell proliferation, cell viability, and gene expression. The surgical feasibility was initially tested by implanting the OPTO-EPIRET in cadaveric rabbit eyes. Afterwards, inactive devices were implanted in six rabbits for feasibility and biocompatibility testings in vivo. In follow-up controls (1-12 weeks post-surgery), the eyes were examined using fundoscopy and optical coherence tomography. After finalization, histological examination was performed to analyze the retinal structure. Regarding the in vitro biocompatibility, no significant influence on cell viability was detected (L929: < 1.3% dead cells; R-28: < 0.8% dead cells). The surgery, which comprised phacoemulsification, vitrectomy, and implantation of the OPTO-EPIRET through a 9-10 mm corneal incision, was successfully established. The implant was fixated with a retinal tack. Vitreal hemorrhage or retinal tearing occurred as main adverse effects. Transitional corneal edema caused difficulties in post-surgical imaging. CONCLUSIONS: The OPTO-EPIRET stimulator showed a good biocompatibility profile in vitro. Furthermore, the implantation surgery was shown to be feasible. However, further design optimization steps are necessary to avoid intra- and postoperative complications. Overall, the OPTO-EPIRET will allow for a wide visual field and good visual acuity due to a high density of electrodes in the central retina.

Authors 11

1. Kim Schaffrath corresponding Aachen Department of Ophthalmology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Department of Ophthalmology, University Hospital RWTH Aachen, Aachen, Germany. kischaffrath@ukaachen.de

   Department of Ophthalmology, University Hospital RWTH Aachen, Aachen, Germany

2. Tibor Lohmann Aachen Department of Ophthalmology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Department of Ophthalmology, University Hospital RWTH Aachen, Aachen, Germany

3. Jan Seifert Aachen Department of Ophthalmology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Department of Ophthalmology, University Hospital RWTH Aachen, Aachen, Germany

4. Claudia Ingensiep Aachen Department of Ophthalmology

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Department of Ophthalmology, University Hospital RWTH Aachen, Aachen, Germany

5. Pascal Raffelberg

   University of Duisburg-Essen

   Affiliation as printed

   Department of Electronic Components and Circuits, University Duisburg-Essen, Duisburg, Germany

6. Florian Waschkowski Aachen Institute of Materials in Electrical Engineering 1

   RWTH Aachen University

   Affiliation as printed

   Institute of Materials in Electrical Engineering 1, RWTH Aachen University, Aachen, Germany

7. Reinhard Viga

   University of Duisburg-Essen

   Affiliation as printed

   Department of Electronic Components and Circuits, University Duisburg-Essen, Duisburg, Germany

8. Rainer Kokozinski

   Fraunhofer Institute for Microelectronic Circuits and Systems · University of Duisburg-Essen

   Affiliation as printed

   Department of Electronic Components and Circuits, University Duisburg-Essen, Duisburg, Germany

   Fraunhofer Institute of Microelectronic Circuits and Systems, Duisburg, Germany

9. W. Mokwa Aachen Institute of Materials in Electrical Engineering 1

   RWTH Aachen University

   Affiliation as printed

   Institute of Materials in Electrical Engineering 1, RWTH Aachen University, Aachen, Germany

10. Sandra Johnen Aachen Department of Ophthalmology

    Universitätsklinikum Aachen · RWTH Aachen University

    Affiliation as printed

    Department of Ophthalmology, University Hospital RWTH Aachen, Aachen, Germany

11. Peter Walter Aachen Department of Ophthalmology

    Universitätsklinikum Aachen · RWTH Aachen University

    Affiliation as printed

    Department of Ophthalmology, University Hospital RWTH Aachen, Aachen, Germany