Abstract
Purpose: :
To evaluate the feasibility of a new implantation technique in vivo and the compatibility of the minimal invasive retinal implant (miRI) for up to 6 months in the nonhuman primate model.
Methods: :
The new concept of this miRI project was the placement of the implant onto the sclera temporally of the fovea to enable penetration of electrodes through sclera, choroidea and retina. With this method, vitrectomy or other treatment in advance of the surgery were not necessary. The implants had up to 10 electrodes and were fixed to remain in the cynomolgus monkey (M. fascicularis) eye for up to 6 months. Compatibility was checked by ophthalmoscopy, fundus photography, IOP, ERG, and VECP measurements as well as histopathology.
Results: :
After surgery, funduscopy showed that single electrodes have been already penetrated. In 4 of 5 animals all remaining electrodes penetrated during the observation period. No retinal detachment was observed and only one animal showed minimal bleeding when one electrode hit a small retinal vessel. An unintended scleral perforation caused by a suture placed for implant fixation led to choroidal bleeding but did not show any complications during the remaining observation time. IOP determinations did not show significant differences between the implanted right and the non–implanted left eye. There were no permanent changes in amplitudes or latencies of the ERG and latencies of the VECP were stable throughout the 6 months period. No proliferative vitreoretinopathy was observed 6 months after surgery.
Conclusions: :
The surgical procedure and the new implants apparently provide a new and feasible concept for implantation onto the sclera and penetration of electrodes through the sclera, choroidea, and retina.
Keywords: retina • electrophysiology: non-clinical • visual impairment: neuro-ophthalmological disease