The Transchoroidal Implantation of Subretinal Active Micro-Photodiode Arrays in Blind Patients: Long Term Surgical Results in the First 11 Implanted Patients Demonstrating the Potential and Safety of This New Complex Surgical Procedure That Allows Restoration of Useful Visual Percepts

Abstract

Purpose: : Active polyimide foil bound subretinal micro-photodiode arrays and their necessary connection to extraocular structures for energy supply require a transchoroidal surgical implantation procedure. A safe surgical transchoroidal procedure for a subretinal access was developed and applied in humans.

Methods: : 11 legally blind patients were paramacularly implanted with a transchoroidal subretinal active prosthetic device. The implant consisted of a stimulation chip with 1500 electrodes on a polyimide film and additional stimulation electrode array with16 electrodes of the same kind. The required energy for the stimulation was delivered via a retroauricular transdermal cable that ended in a transchoroidal polyimide foil carrying supply lines. Experiments were carried out successfully in patients with chronic subretinal implants via direct stimulating electrodes or with light stimuli via the chip. Implants had to be removed according to study protocol after 30 days with an extension to 3 month in the last 3 patients. Radiodiathermy with precise adjusted parameters allowed to penetrate the choroid without any bleeding. Specially designed guiding foils that were modified during the trial were used for implantation. Silicone oil served as a tamponade.

Results: : Implantation was successfully performed in all 11 patients. No surgically induced adverse events were observed during the complex surgical procedure or the follow up period of up to 3 years. The implants remained stable in all cases during the stimulation period and delivered unique results as will be reported by Zrenner et al. One patient refused the explantation and kept the implant. This patient was closely monitored for 3 years.

Conclusions: : The newly developed transchoroidal implantation and explantation procedure was successfully established in humans and applied in 11 patients. This procedure enables a safe chronic stable subretinal implantation of large electronic arrays which are the basis for the successful stimulation experiments and the further development of the subretinal chips to restore useful visual percepts in blind patients.

Clinical Trial: : www.clinicaltrials.gov NTC00515814

Keywords: retina • vitreoretinal surgery • retinal degenerations: hereditary