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G. Richard, M. Feucht, N. Bornfeld, T. Laube, G. Rössler, M. Velikay–Parel, R. Hornig; Multicenter Study on Acute Electrical Stimulation of the Human Retina With an Epiretinal Implant: Clinical Results in 20 Patients . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1143.
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Purpose: To determine thresholds for eliciting visual perceptions by acute electrical stimulation of the human retina using an epiretinal implant and to characterize the respective visual perceptions in subjects suffering from retinitis pigmentosa. Methods: A total of 20 patients, 14 male and 6 female, were included in a multicenter study applying strict inclusion and exclusion criteria. Patients’ mean age was 55 years (range, 35 to 75 years). Visual acuities ranged from 1/50 to no light perception. Stimulation procedure was done during a pars plana vitrectomy with a maximum duration of 45 minutes. For stimulation a microcontact film with IrOx–electrodes, manufactured by IIP–Technologies, Bonn, Germany, connected by cable to a current generator was positioned epiretinally in the macular area. After repeated stimulation, the microcontact film was removed. Standardized interviews were performed 15 and 90 minutes after operation. The study completely fulfils the conditions of the German medical device law, GCP–guidelines and the declaration of Helsinki. Ethic’s committees authorized the protocol. Results: Overall 19 of 20 subjects reported one or more electrically evoked perceptions in close time correlation to single stimulation events. Pleasant and not flashy perceptions of coloured objects ranging in size from a head of a match to a football as seen from a distance of one meter were reported. Even a patient blind for 25 years had relevant and reproducible visual perceptions. Threshold charges needed to generate visual perceptions proved to be different between individual patients and ranged from 20 to 380 nC with single electrodes. Except for retinal detachment in one patient (reattached), no other side effects, especially no damage to the macula, were observed during the 3–month follow–up. Conclusions: Acute electrical stimulation of the human retina using microcontact films may create useful visual perceptions even in totally blind patients. It proved to be efficient and safe. Results are encouraging with regard to the implantation of a chronic epiretinal implant.
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