If a patient with retinitis pigmentosa experiences increasing peripheral vision loss, what explains why gene therapy targeting photoreceptor survival might fail to fully restore vision?

💡 Explanation

Gene therapy restores photoreceptor function but does not address subsequent degeneration of the bipolar cell network; because this network transmits signals, its loss prevents complete vision restoration. Therefore, the gene therapy, rather than failing directly on photoreceptors or drug delivery, is limited by downstream effects.

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