Purchase this article with an account.
H.M. Sailer, H. Loeffler, R. Wilke, E. Zrenner; Subretinal Chronic Multi–Electrode Arrays Implanted in Blind Patients: Device and Procedure for Testing Perception Elicited by Direct Stimulation . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3208.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Development of devices that allow wireless transmission of stimulation parameters to subretinal electrode arrays, implanted chronically in blind patients for direct stimulation as well as definition of procedures to study perception mediated by such devices.
A 4x4 electrode array (electrode dimension 50x50 µm, spaced 280 µm), positioned on a small, chronically implanted subretinal polyimid foil is connected through a transchoroidal, transscleral connector foil to a retro–auricular transdermal cabel ending in a small radio–controlled battery driven stimulation box. Stimulation parameters for each electrode can be controlled independently by a comfortable software, that allows to transform the orientation of the visual space to the orientation of the electrode field and to set individual stimulation parameters in the stimulation box via a wireless transmitter. Moreover, all stimulation parameters and patient’s "yes" or "no"–responses to each parameter are recorded automatically by the software. The battery capacity allows investigation for approximately 8 hours.
In two patients the perception thresholds for individual electrodes and various combinations of electrodes were assessed by varying charge injection via an up and down threshold assessment procedure. Thresholds and perceptual correlates can be assessed for electrical stimuli varying in amplitude, sequence (monophasic, bi–phasic, anodic first, cathodic first), duration, burst frequency, interstimulus interval by simultaneous or successive addressing of individual electrodes. This allows to present a large variation of software–controlled temporal and spatial patterns, successfully applied to two patients (see Zrenner et al. 2006, Wilke et al. 2006).
The software–controlled stimulation set–up, designed for addressing subretinal electrode arrays via wireless control has been successfully applied to blind patients in order to assess electrically evoked local threshold perceptions, as well as repetitively presented spatially static patterns for prolonged perception and dots moving in various directions, in order to optimize parameters that allow correct recognition of alternative forced choice presentation of various patterns.
This PDF is available to Subscribers Only