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N. Stupp, B. Niggemann, H. Gerding; The Minimal Invasive Retinal Implant (miRI) Project: Development of Surgical Techniques and Experimental Testing in a Series of Primate Implantations . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3191.
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To develop and test surgical techniques for the implantation and mechanical stabilisation of a minimal invasive retinal implant (miRI) and to define a procedure for the later application of miRI–implants in humans.
Implantation, scleral penetration of stimulation electrodes, and mechanical stabilization of implants were tested in a three step approach including: experimental series in vitro with 1. donor eyes of rabbits, monkeys and humans (not suitable for corneal donation, 2. cadaver skull specims of rabbits and monkeys. Surgical techniques developed within these experiments were applied in a series of in vivo implantations of prototypes in 5 monkeys (M. fascicularis). Experiments were documented by digital image processing and eyes of in vitro experiments were dissected following implantation. Eyes of in vivo experiment were checked for surgical complications and introduced into a standardized long–term protocol.
In vivo experiments clearly demonstrated that sclera and choroid can simultaneously be penetrate by 10 electrodes in eyes of all species. Intrascleral sutures were effective and safe for the stabilization of electrode pads. The defined optimal implantation procedures was including the following steps: 1. conjunctival sections, 2. ligature of superior & inferior rectus muscle, 3. desinsertion of lateral rectus muscle, 4. partial desinsertion of oblique muscles, 5. marking of implanat position, 6. insertion of the implant and penetration of sclera & choroid by penetrating electrodes, 7. implant stabilization by episcleral sutures, 8. reinsertion of lateral rectus muscle, 9. closure of tenon and conjunctiva. The only intraoperative complications were limited choroidal hemorrhages (1x by perforated suture, 1x minor bleeding by on electrode). Immediate funduscopy revealed that not all electrodes were penetrating the eye at once. Nearly all electrodes invaded the eye under permanent tension of fixation sutures within the first weeks after implantation.
Results of in vitro and in vivo implantations showed that miRI–type implants with transsclerally penetrating electrodes can safely be implanted and mechanically fixated in non–human primate eyes. Email: hgerding@klinik–pallas.ch
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