Downstream Effects of Photoreceptor Degeneration and Electrical Retinal Stimulation on Visual Cortex Macrostructure and Function

Visual prostheses are a possible treatment for retinal degenerate conditions. Research in visual protheses and blindness should consider the effect of retinal electric stimulation on the central visual pathway in respect to cortical structure and function. Transcorneal Electric Stimulation was used to electrically activate the retina and immunohistochemistry analysis of visual cortex was performed. Cortical layer thickness of primary visual cortex after photoreceptor degeneration in P23H rats was maintained compared to sighted rats at ages P120, P180, and P360. Transcorneal stimulation applied weekly or twice weekly did not results in differences in cortical thickness. C-Fos (a biomarker of neural activity) showed a weak trend towards reduced expression in cortex corresponding to retinal stimulation, counter to our expectation.