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Jonathan Yeoh, Alexia Saunders, David Nayagam, Chris Williams, Mark McCombe, Burns Owen, Joel Villalobos, Michelle McPhedran, Robert Briggs, Penelope Allen, ; Development of a surgical procedure for implanting a wide view electrode array in the suprachoroidal space. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1028.
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The goal of this study was to develop the surgical procedure for implanting a suprachoroidal retinal prosthesis in patients. The preclinical implant was adapted to conform to human orbital anatomy.
A surgical technique for suprachoroidal implantation of a conformable electrode array (19 mm × 8 mm) and lead was developed. Human cadavers (n = 5) were used to adapt the approach which was previously used in a pre-clinical model . A method of tunnelling the array forward from behind the pinna towards the orbit was used, with a custom trocar. First, an anteriorly based C-shape flap was created behind the pinna to position the percutaneous pedestal. Next a lateral canthotomy was made. An orbitotomy was drilled in the frontal process of the zygomatic bone, 10 mm below the orbital suture line. The lead was anchored inside this notch with a compression fit and by a conformable patch sutured onto the sclera. The lateral rectus muscle was detached and a 9 mm full scleral thickness incision was made 1-4 mm behind the muscle insertion point, according to eye size. A pocket was created in the suprachoroidal space. The moulded array was inserted into the suprachoroidal space . The incision was closed and scleral anchor point sutured.
Dissection of the cadaver eyes confirmed that the retinal prostheses were reliably positioned in the suprachoroidal space and beneath the macula. A conformable anchor point sutured to the sclera stabilised the transscleral lead exit. This anchor point was angled accordingly to ensure a simple fit of the intraorbital lead with minimal strain. Safe tunnelling was achieved with the use of a tunnelling trocar beneath the temporalis facia. The 150 mm lead reliably reached the pedestal behind the pinna.
A surgical approach for suprachoroidal prosthetic implantation was developed for successful anatomical placement, mechanical stability and safe tunnelling, to be used in subsequent patient testing. Electrode impedance measurements and psychophysics testing in patients have shown the retina to be functional after uncomplicated surgery and several months of implantation.
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