Article
A suprachoroidal retinal prosthesis: surgical safety and stability
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Published: | December 10, 2019 |
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Objective: The success of our prototype clinical trial (NCT01603576) of a suprachoroidal retinal prosthesis led us to develop a second generation fully implantable device, with the aim of providing visual information to profoundly visually impaired patients.
Materials and methods: Four patients (P1, P2, P3 and P4) with end-stage rod - cone dystrophy and perception of light visual acuity were implanted with a 44 channel electrode array in the suprachoroidal space connected to a subcutaneous receiver stimulator during 2018 (NCT03406416). After recovery they commenced transcutaneous stimulation of the device. Post operative follow-up included clinical examination, fundus photography and optical coherence tomography (OCT) to assess surgical recovery and impact on the eye. OCT imaging was used to track the retinotopic location of the leading edge of the implant. The translation and rotation of the array relative to baseline (1 week post-implantation) was calculated at regular review for all four patients.
Results: The surgical procedures took between 204 and 260 minutes and were uncomplicated. At the completion of surgery, impedance testing showed in all patients, all electrodes were functional. Post operative recovery was uneventful. Fundus imaging and OCT imaging confirmed the device position and the absence of retinal trauma. Fundus imaging showed movement only in P3. OCT imaging showed some movement of the device and for P1, P2, and P3, movement was primarily rotational, while for P4 movement was primarily translational.
Discussion: A retinal prosthesis can be safely implanted in the suprachoroidal space. Over twelve – eighteen months of follow-up clinical findings, fundus photography and OCT imaging confirm safety and stability of the approach with no serious adverse events and only slight movement on OCT imaging. Only P3 had significant movement in both dimensions however this settled spontaneously.