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G.Y. Fujii, M.S. Humayun, J. Weiland, R. Greenberg, B. Mech, J. Little, J.V. Rossi, D. Yanai, M.K. Tameesh, C.Q. Panzan; Intraocular Retinal Prosthesis: First Generation Implant and its Surgical Technique . Invest. Ophthalmol. Vis. Sci. 2003;44(13):5079.
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Purpose: To present the final design of the first generation intraocular retinal prosthesis and the surgical technique for its implantation. Methods: The Second Sight Model 1 retinal prosthesis (SSM 1) consists of an extraocular microelectronic device and an intraocular electrode array, connected by a multiwire cable. Throughout the SSM 1 development, several versions were created and tested. Specifically, arrays with various designs and its mechanical and biological retinal effects were evaluated. The numbers of retinal tacks, its design and positioning to secure the array on the retinal surface were studied. Eighteen mixed-breed and 5 blind dogs were used to develop the SSM 1 design. Several surgical techniques were employed and evaluated in order to obtain the safest and most stable implantation. The follow-up examination included indirect ophthalmoscope evaluations (weekly), fundus photographs (monthly), electroretinography testing (monthly) and histological study after six months. Results: Initial experiments using 2-3 tacks and early array designs revealed damage at the edges of the array and inflammation between the tacks. Refinement of the array and tack design and improvement in the surgical technique have resulted in a single-tack technique with a stable implant during the follow-up period. This method has been used in 5 dogs to date. In these dogs, retinal tacks and the retinal array remained firmly affixed to the retina throughout the follow-up period of at least 6 months. Mild hyperpigmentation of the RPE and minimal retinal folds were observed only around the site of retinal tack insertion and were minimized with improved array and tack design. A- and b-wave amplitudes of the electroretinogram were not statistically different from the normal unoperated fellow eye. Fluorescein angiography showed that the entire retina including the area under the electrode array remained well perfused. Histologic evaluation revealed near total preservation of the retina underlying the electrode array. No severe complications occurred in any of the animals. The implantation of extraocular portion of the SSM 1 was not associated with complications. Conclusions: A first generation prosthesis (SSM 1) and a surgical technique for its implantation were developed. The SSM 1 is both mechanically and biologically compatible and its surgical technique is safe and associated with stable long-term implantation.
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