Recovery of Vision in Experimental Animals: Optic Nerve Regeneration and Reconstruction of Central Pathway

Abstract

Retinal ganglion cells (RGCs) and their axons (optic nerve; ON) provide a good experimental model for research on damaged CNS neurons and their functional recovery. After the ON transection most RGCs degenerate retrogradely but they can be rescued and regenerated in some extent by transplantation of a piece of peripheral nerve (PN). When the nerve graft was bridged to the visual center, the central visual projection of regenerating RGC axons can be formed and the behaviors based on relatively simple visual function can be restored in rodents. Axotomized RGCs in adult cats are also shown to survive and regenerate their axons through the PN graft. Among the cat RGC types, Y cells (α-cells) tend to survive and regenerate axons better than others. X cells (β-cells), which are essential for central vision, suffer from rapid death after ON transection. To improve survival and axonal regeneration of axotomized RGCs, intravitreal injections of various neurotrophic factors and electrical stimulation to the ON are effective. To restore visual function in adult mammals with damaged optic pathway, the comprehensive and integrative strategies of multiple approaches will be needed.