Stephanie Saltzmann¹, Noelle Stiles¹, Jeiran Choupan², Yonggang Shi²; ¹Rutgers University, ²University of Southern California

The Argus II retinal prosthesis is designed to electrically stimulate the remaining retinal ganglion cells in patients with Retinitis Pigmentosa, a condition that causes progressive vision loss. Research indicates that the onset of blindness, especially at an older age, leads to significant structural changes in the brain, particularly in the cortical and subcortical regions associated with spatial processing, such as spatial navigation, awareness, and memory. These brain regions undergo reorganization to compensate for the loss of vision, and it remains uncertain how visual restoration through devices like the Argus II influences the thickness or volume of these areas compared to sighted individuals. This study measured cortical and subcortical thickness in three groups: ten Argus II patients, ten blind individuals, and thirteen sighted controls. The focus was on regions important for spatial cognition, such as the parahippocampal gyrus and the hippocampus. The findings revealed that, on average, Argus II patients showed a thicker left parahippocampal gyrus than blind patients, suggesting that the device may facilitate structural changes in the brain. In the two case studies, the shorter-using (6.5 months) and longer-using (44.5 months) patients showed an increase in the thickness of the parahippocampal gyrus. In the third case study, there was an increase in the thickness of the left parahippocampal gyrus from 43.5 to 57 months and beyond 106 months of disuse. The right parahippocampal gyrus thickness and right hippocampus volume positively correlated with the duration of experience with the device. The results suggest that using the Argus II device may facilitate structural plasticity in the brain, particularly in spatial memory and navigation regions. This finding underscores the potential for the brain to adapt and reorganize, even in late-blind patients, as they relearn to interact with their environment through restored vision.

Acknowledgements: The National Institutes of Health, National Eye Institute (1U01EY025864); the National Institutes of Health, the BRAIN Initiative (5K99EY031987 and R00EY031987).