title: Biocompatibility and durability of Teflon-coated platinum-iridium wires implanted in the vitreous cavity.
abstract: Teflon-coated platinum-iridium wires are placed in the vitreous as electrodes in artificial vision systems. The purpose of this study was to determine whether these wires have toxicity in the vitreous cavity, and to examine the durability of their coating when grasped by forceps. Rabbits were implanted with platinum-iridium wires that were 50 μm in diameter and coated with Teflon to a total diameter of 68 or 100 μm. To examine the biocompatibility, electroretinograms (ERGs) and fluorescein angiography (FA) were performed before and 1 week, 1, 3, and 6 months after the implantation of the electrode. After 6 months, the eyes were histologically examined with light microscopy. To check the durability, the surface of a coated wire was examined with scanning electron microscopy after grasping with different types of forceps. At all times after the implantation the amplitudes and implicit times of the ERGs recorded were not significantly different from those recorded before the implantation (P > 0.05). FA showed no notable change during the follow-up periods. Histological studies showed that the retinas were intact after 6 months of implantation. There was no damage to the Teflon-coated wire after grasping the wire with forceps with silicon-coated tips, while surface damage of the Teflon that did not extend to the platinum-iridium wire was found when grasped by vitreoretinal forceps. We conclude that Teflon-coated platinum-iridium wire is highly biocompatible in the vitreous for at least 6 months. Wires should be handled with vitreoretinal forceps with silicone-coated tips in order to avoid causing damage during wire manipulation.
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Osaka 565-0871, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nishida
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Sakaguchi
authors.forename: Ping
authors.initials: P
authors.lastname: Xie
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Terasawa
authors.forename: Motoki
authors.initials: M
authors.lastname: Ozawa
authors.forename: Motohiro
authors.initials: M
authors.lastname: Kamei
authors.forename: Kohji
authors.initials: K
authors.lastname: Nishida
mesh_terms: D000792:Angiography; D000818:Animals; D003287:Contrast Media; D004567:Electrodes, Implanted; D004596:Electroretinography; D019793:Fluorescein; D007495:Iridium; D008422:Materials Testing; D009887:Ophthalmoscopy; D010984:Platinum; D011138:Polytetrafluoroethylene; D011475:Prosthesis Failure; D019919:Prosthesis Implantation; D011817:Rabbits; D012160:Retina / Q000033:anatomy & histology; D057488:Visual Prosthesis
chemical_list: D003287:Contrast Media; C077763:platinum-iridium alloy; D007495:Iridium; D010984:Platinum; D011138:Polytetrafluoroethylene; D019793:Fluorescein