Surgical Technique for Implantation 3D Wide Field Array - A New Design for an Epi-Retinal Prosthesis Interface

Abstract

Purpose: : To develop and establish a surgical method for safe implantation of a novel epi-retinal prosthesis stimulating array designed to provide both central and peripheral vision.

Methods: : A novel array was designed, consisting of a central part with 37 electrodes (0.15 mm diameter) and two external wings with 12 electrodes (0.5 mm diameter) on each wing. The array also had a ribbon cable (2 mm width) for connecting electrodes with extraocular electronics. The array substrate is polyimide and the metal is platinum. After fabrication, the array is thermally formed to take the shape of the eye with radii of curvature of 11-13 mm. The array is circular with a diameter of 10.9 mm. The wings can be folded in to a custom delivery device for insertion into the eye within a relatively small of the scleral incision. After complete pars plana vitrectomy, a scleral wound of 3.2mm was made to insert the delivery device into canine eye. At a safe distance from the retina and the lens, the array was inserted and opened. The array’s central part was positioned over the area centralis and the array’s wings over the arcade vessels.

Results: : The array was implanted in six canines. In all implants the array was easily inserted into the eye and unfolded. A single retinal tack was used to secure the array to the retina. Intraoperatively a minor hypotony occurred when the array was implanted, no lens and visible array damage occurred. In one case a peri-operative iris bleeding appeared. During the fixation of the array we observed in the first two dogs the central part of the implant folded the retina. The array was modified to decrease the radius of curvature and change the angle of the cable to direct the cable away from the retina. The last four surgeries used the modified array and no peri-operative retinal folds were present.

Conclusions: : A wide-field array could be inserted through a sclerotomy 1/3 the diameter of the array, suggesting a possible method for providing peripheral vision. The surgical procedures are feasible.

Keywords: retinal degenerations: hereditary • vitreoretinal surgery • development