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A. Kolck, S. Mueller–Kaempf, B. Sellhaus, S. Taneri, H. Gerding; Experimental implantation of combined anterior/posterior segment retinal prosthesis in rabbits: results of long–term observation. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4220.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the feasibility of surgical procedures and long–term outcome of eyes after implantation of anterior/posterior segment retinal prostheses. Methods: 2 different types of implants were used in rabbits: 1. type I implants consisting of posterior segment microcontact foils connected to standard IOL's, and 2. final–version (type II) encapsulated retinal implant prototypes. All devices were electrically inactive. Principle steps of surgical procedures were: phacoemulsification, vitrectomy, posterior capsulotomy, guidance of microcontacts close to the posterior pole, and stabilization of microcontacts mainly with hybrid microtacks. In 6 cases a corneoscleral/clear cornea approach was used, in two cases open–sky implantation was applied. Follow–up covered 3–12 (median: 6.5) months including funduscopy, photography, echography, and electroretinography. Post mortem evaluation was performed by standardized macropathological, histological and immunhistochemical examinations. Results: During implantation intensive anterior segment exsudation of fibrin was setting limits to the surgical approach in 4 eyes. Posterior segment procedures were uneventful in all cases. Postoperatively 6/8 eyes presented a persistent keratopathy. In one case with open–sky approach perforating keratoplasty was necessary after 6 months. Retrocorneal membranes developed in 3/8 eyes. Significant cyclitic membrane formation was observed in 5/8 eyes. 3 eyes developed severe PVR with total retinal detachment at final observation. Another 3 eyes developed significant epiretinal traction resulting in circumscript retinal detachment. Decentration, subluxation, or tilting of implants was observed in 5/8. Histology generally presented relatively extensive proliferations accompanying microcables especially in the ciliary region, anterior retina, and at the posterior segment position of microcontacts. One of the type II implants presented leakage of implant encapsulation and secondary oxidative changes. Relatively favourable results were observed only in 2 eyes with type I implants and well preserved lens capsule. Conclusions: According to the results of this series the implantation of complex retinal prostheses has to be regarded as a surgical procedure with a critical prognosis. Major problems are the development of cyclitic membranes, epiretinal proliferations and implant dislocation.
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