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J. Chen, S. Kim, J. Brookman, L. Snebold, M. Kenney, D. Shire, J. F. Rizzo, III; Surgical Methods for Large Sub-Retinal Prosthetic Implantation. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2562.
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© ARVO (1962-2015); The Authors (2016-present)
This work is related to the efforts of the Boston Retinal Implant Project to develop a sub-retinal prosthesis to restore vision to the blind. The specific purpose of this presentation is to develop a safe surgical method to implant a relatively large electrode array sub-retinally.
The eyes of 19 Yucatan mini pigs were studied, 4 of which underwent survival surgeries and 15 had acute surgeries. Inactive, micro systems PI-2611 polyimide arrays that were 16 µm thick with 100 Iridium Oxide electrodes 200 µm in diameter were used in survival surgeries. The array is 5 mm in diameter, which could theoretically provide vision over >15° of visual angle. To avoid excessive bleeding during surgery, systemic hypotension was maintained. 2 ab externo methods were used: (1) choroidectomy without retinal detachment and (2) choroidotomy with induced retinal detachment. A scleral flap was dissected posterior to the limbus temporally followed by vitrectomy. In method 1, scleral fibers were shaved away, a choroidectomy was made, the array was placed on the retina and the flap was sutured. In method 2, a local retinal detachment was made underneath the flap. Scleral fibers were shaved away and a choroidotomy was made. The array was inserted using a guide.
Of 14 acute surgeries with choroidectomy, 5 resulted in successful implantation of an array (See 2005 ARVO abstract). Of 2 survival surgeries with choroidectomy, 1 resulted in the retina bulging out which only allowed for insertion half way into the sub-retinal space and 1 surgery failed because of retinal tear. 1 acute surgery and 1 chronic surgery with choroidotomy were successful. In 1 survival surgery with choroidotomy, the pig died.
Large arrays can be sub-retinally implanted. The method utilizing a choroidotomy with induced retinal detachment facilitated implantation of our relatively large electrode array. More experiments will be performed to gain further experience with this procedure.
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