Article
Perception of motion in a 2nd generation suprachoroidal retinal implant
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Published: | December 10, 2019 |
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Outline
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Purpose: To determine whether perception of motion is achievable with a 2nd generation suprachoroidal retinal implant.
Methods: Three participants (PA, PB, PC) implanted with a 44-channel suprachoroidal retinal implant performed a 4AFC motion discrimination task. Stimuli were a single white vertical or horizontal 5° wide bar that swept left, right, up, or down at 7, 15, or 30°/s across a black background on a 42” monitor at arm’s length. The change in eye (ΔEye) and head (ΔHead) position between stimulus onset and offset was calculated for each trial and the effect of stimulus direction was tested using a MANOVA. Smooth pursuit movements, generally not possible without a moving target, were identified using a gaze velocity criterion and indicated retinotopic perception of motion versus reliance on secondary cues such as head scanning.
Results: Accuracy on the task was: PA 41.7%; PB 66.3%; PC 87.2%. For all participants a significant effect of stimulus direction on ΔEye and ΔHead was detected, but only when the response was correct. PA only attempted 7°/s stimuli. ΔEye and ΔHead both followed the stimulus direction (p<0.001). PB exhibited multiple strategies: for 7°/s stimuli only ΔHead followed the stimulus (p<0.001); for 15°/s both ΔEye and ΔHead followed the stimulus (p<0.001); for 30°/s only ΔEye followed the stimulus (p<0.001) and ΔHead was minimal. For PC ΔHead was minimal and ΔEye followed the stimulus direction for all stimulus speeds (p<0.001). Smooth pursuit contributed significantly to the eye response for PB and PC, suggesting retinotopic perception of motion.
Conclusion: Motion discrimination is possible with a 2nd generation suprachoroidal retinal implant, and sequential stimulation of electrodes can elicit perception of motion. Acknowledgements Industry support from Bionic Vision Technologies Pty Ltd; Operational Infrastructure Support from the Victorian Government.