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R. Freda, D. Gouven, H. Ameri, R. Agrawal, O. Auciello, J. Weiland, M. Humayun; Ultra Nano Cristallyne Diamond (UNCD) film as Hermetic Coating for Encapsulation of the Epiretinal Microchip– Biocompatibility Study . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3185.
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To investigate the long–term safety of intravitreal implantation of UNCD in vivo
A 5 x 5 mm2 of UNCD coated pieces of silicon were implanted through the pars plana into the vitreous cavity of the right eye of 10 rabbits without performing any vitrectomy. The left eye was used as a control. Anterior segment evaluation, color fundus photography, fluorescein angiography, electroretinography, and OCT were obtained preoperatively and at 1–month intervals for 6 months postoperatively. Five rabbits were sacrificed after 6 months of follow–up and the eyes were enucleated. Two rabbits were sacrificed at 2 months, one rabbit at 7 weeks and another one at 2 weeks. One rabbit died after 2 month examination anesthesia injection. Morphologic retinal alterations were assessed by light microscopy
No signs of intraocular inflammation or infection occurred in any of the animals during the follow–up period. Two rabbits developed retinal detachment due to the sharp edges of the silicon chip (mechanical trauma) at 2 month. In the remaining rabbits, ERG data showed A– and b–wave amplitudes, implicit time and latencies stable throughout the follow–up time as compared to baseline. Color fundus photography and fluorescein angiography showed no morphological retinal alterations. OCT did not reveal any abnormal retinal thickening. Similarly, histological evaluation showed adequate preservation of the retina and choroid
Intravitreal UNCD appears to be well tolerated after long term implantation in rabbits. Standard cleaved silicon chips with chip level coatings can potentially damage the retina
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