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Visualisation of active subretinal implants with external connections by high-resolution CT
  1. Florian Gekeler1,
  2. Andreas Kopp2,
  3. Helmut Sachs3,
  4. Dorothea Besch1,
  5. Udo Greppmaier4,
  6. Eberhart Zrenner1,
  7. Karl Ulrich Bartz-Schmidt1,
  8. Peter Szurman1
  1. 1Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
  2. 2Department of Radiology, University of Tübingen, Tübingen, Germany
  3. 3Klinikum Friedrichstadt, Dresden, Germany
  4. 4Retina Implant AG, Reutlingen, Germany
  1. Correspondence to Dr Florian Gekeler, Centre for Ophthalmology, University of Tübingen, Schleichstrasse 12-16, Tübingen, Germany; gekeler{at}


Two patients carrying an active subretinal implant with extra-ocular parts were examined by high-resolution CT. Cranial scans were acquired in the primary position and in eight additional directions of gaze with eyes open and closed to demonstrate the mobility of the eyeball and the implant within the orbital cavity. Three-dimensional images were constructed to visualise the path of the implant from the retro-auricular space around the lateral orbital rim through the orbit and within the subretinal space up to the device's final para-foveal position. Images were obtainable in high quality, resulting in three-dimensional models illustrating all parts of the implant including the micro-photodiode array at the tip in the subretinal space. The implant followed eye movements in all directions of gaze; eye movements were only minimally restricted as described in previous publications. Since all, except intra-ocular, parts of the implant evade direct examination, CT can be useful to assess the technical integrity and the biocompatibility and biostability of retinal implants.

  • Retinal implant
  • prosthesis
  • CT
  • subretinal
  • retina
  • orbit
  • imaging

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  • Funding The retinal implant was manufactured and delivered by Retina Implant AG (Reutlingen, Germany), which also covered the direct costs of the study.

  • Competing interests According to the journal's guidelines, the authors declare the following competing interests: (1) the retinal implant was manufactured and delivered by Retina Implant AG (RIAG), Reutlingen, Germany; (2) RIAG covered the direct costs of the study; (3) HS, EZ and FG are shareholders of RIAG; none of them receives payment or is employed by RIAG.

  • Patient consent Obtained.

  • Ethics approval This study was conducted with the approval of the Ethics Committee of the Medical Faculty of the University of Tuebingen, Germany. All procedures adhered to the Declaration of Helsinki.

  • Provenance and peer review Not commissioned; externally peer reviewed.