Predicting Visual Sensitivity in Retinal Prosthesis Patients

Abstract

PURPOSE With the long-term goal of restoring functional vision in patients with retinal degenerative diseases, the eyes of blind human subjects were implanted chronically with epiretinal prostheses consisting of two-dimensional electrode arrays that directly stimulated cells of the neural retina. METHODS Psychophysical techniques were used to measure the brightness of electrically generated percepts on single electrodes using a variety of electrical stimulation patterns. RESULTS It was possible to predict the sensitivity of the human visual system to a wide variety of retinal electrical stimulation patterns using a simple and biologically plausible model. CONCLUSIONS This is the first study to demonstrate that, on the single-electrode level, retinal electrical stimulation in humans can produce visual qualia that are predictable using a quantitative model, a prerequisite for a successful retinal prosthesis.

Response variability to high rates of electric stimulation in retinal ganglion cells

“…Although the results of Horsager et al (2009) in conjunction with our findings suggest that higher rates of spiking are associated with lower thresholds, it is important to point out that uniform delivery of high-rate pulse trains may not be the optimum stimulation strategy. Different types of ganglion cells each typically respond to visual stimuli with different spike frequencies (DeVries and Baylor 1997;Roska and Werblin 2001), and therefore it is probably not desirable to generate similar rates of high-frequency spiking in all types.…”

“…For example, Horsager et al (2009) found that the thresholds for eliciting percepts decreased as the rate of stimulation was increased. Presumably, changes in the rate of stimulation alter the rate at which spikes are elicited in targeted ganglion cells.…”

Morphological alterations in retinal neurons in the S334ter-line3 transgenic rat

“…Despite widespread morphological changes in the retina, various studies have shown the ability of ganglion cells in RD models to preserve their intrinsic firing properties (Jensen and Rizzo 2008;Margolis et al 2008;Stasheff 2008). Other investigations have exhibited the capability of higher order centers of visual processing to respond to electrical stimulation in such RD animal models (DeMarco et al 2007;Chan et al 2008) and also in clinical trials of retinal prosthesis (Caspi et al 2009;Horsager et al 2009). Furthermore, some studies have shown the preservation of ganglion cell morphology (Mazzoni et al 2008).…”

Pulse trains to percepts: the challenge of creating a perceptually intelligible world with sight recovery technologies

“…However, a variety of psychophysical [19][20][21][22][23][24] and retinal [25] data, as well as the potential distortions described in this review, suggest that this 'linear scoreboard' model is inadequate as an encoding model. To take the development of cochlear implant technology as a guide, a combination of psychophysical and neurophysiological research has led to dramatic improvements in cochlear implant coding schemes over the years.…”