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H Gerding, RE Eckmiller, R Hornig, V Ortmann, A Kolck, S Taneri; Safety Assessment and Acute Clinical Tests of Epiretinal Retina Implants . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4488.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To establish and perform procedures for acute tests of epiretinal stimulation with microcontact foils in humans. Methods: To approach clinical tests, the following sequence of experiments was performed: 1. standardization and evaluation of the surgical technology of implantation and epiretinal placement of band-like microcontact foils (width: 1 mm) in several preliminary and a final test series (n=10) of in vitro-experiments in porcine eyes, 2. in vivo-testing of the same procedure in a series of primate monkeys (M. fascicularis, n=5) , 3. examination of the susceptibility of the human lens capsule towards mechanical impact set by foil electrodes (donor eyes, micromanipulator 200µm/sec or 10µm/stepwise, n=5), and 4. clinical application of microcontact foils during vitrectomy procedures with subsequent evaluation of perceptual responses elicited in human volunteers (Eckmiller et al., ARVO 2002). Results: Experimental implantation of microcontact foils in animal eyes clearly proved that an atraumatic insertion and epiretinal placement can be achieved reproducably in vitro and in vivo by the standardized surgical procedure defined in this series of experiments. Movement of microcontact foils onto human donor eye lenses did not result in capsular penetration even with multiple repetition (50x) of mechanical impact. Histological analysis of contacted retinal areas presented an unaltered structure and a well preserved internal limiting membrane. In humans, microcontact foils could be safely handled in the vitreous space and placed on the epiretinal surface precisely at previously determined coordinates of the fundus. Microelectronic stimulation of the contacted retina in human volunteers resulted in visual perception with charge injection well below the tolerable upper limit for the type of electrodes used. Postoperative psychophysical testing of contacted retinal areas proved the atraumatic character of electrode contact and local stimulation. Conclusion: Epiretinal implantation of microcontact foils is a safe and atraumatic surgical procedure that can be clinically applied for the purpose of preliminary evaluation of perceptual responses in humans and for the future service provided by an epiretinal visual prosthesis.
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