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R. Freda, D. Yanai, J.D. Weiland, M. Mahadevappa, R.J. Greenberg, V. Cimmarusti, G.Y. Fujii, E. deJuan, Jr, M.S. Humayun; Pre and post–operative evaluation in the selection of patients for acute epiretinal electrical stimulation . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4207.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose To report the initials results of a clinical trial of acute electrical retinal stimulation and to describe preoperative tests outcomes used in the selection and postoperative evaluation of subjects in the trial. MethodsThe FDA granted an IDE and USC–IRB approved the study protocol. After obtaining informed consent, 4 subjects were screened preoperatively using visual acuity, psychophysical perception tests (dark–adapted bright flash detection –BF–) and electrophysiological tests (EER, ERG and VEP). In an operating room using local anesthesia, intraocular electrical stimulation (IOS) was performed and thresholds were recorded. Post–operatively patients underwent BF at 2 months, 6 months and 12 months. The BF test consisted of using a xenon flash with different filters intensities to evaluate light–elicited perceptions. The final scale used for analysis ranged from 7.4 dB (dimmest light) to 0 dB (brightest light). Subjects unable to perceive the brightest possible flash were designated as having no flash perception (NFP). EER currents ranged from 0 to 8 mA with a pulse width of either 2ms or 4 ms. IOS consisted of pars plana vitrectomy with positioning of the electrode array on the internal limiting lamina of the retina in the macular region, performing electrical stimulus controlled by computer. Results Preoperatively all subjects had visual acuity of either light perception (LP) or no light perception (NLP) as a result of end–stage retinitis pigmentosa. All subjects had non–recordable dark–adapted ERG and light–adapted VEP. Preoperative BF ranged from no flash detection (NFD) to 4.7db (average was 3.5). Postoperatively BF did not show improvement in the stimulated eye when compared with control eye. Preoperative EER threshold varied from 2mA to 8 mA (2 ms pulse) and from 3mA to 6mA (4 ms pulse). All stimulated eyes, including the NLP eye, did present a positive EER response even the NLP eye. IOS showed a wide variation among subjects, ranging from 147.2 to 1,931 nano coulomb (nC). Subjects with lower preoperative BF had a trend for present a lower IOS levels (r = –.945; p < .05). Conclusion BF test may be used in order to predict lower IOS values and finally better candidates for retinal implant. Acute IOS did not show a protective effect in this small group of subjects.
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