Optic Nerve and Retinal Ganglion Cell Protection, Rejuvenation, and Regeneration as Glaucoma Treatment Strategies

Once destroyed, neurons and their axons in the mammalian central nervous system, including retinal ganglion cells (RGCs) and their axons in the eye and neurons in the thalamic and cortical brain regions involved in visual perception, cannot automatically be replaced. Intrinsic inhibitory chemicals and structural components, suppressive transcription factors, scar formation, and the sheer long distances the RGC axons have to travel to the brain prevent or reduce regenerative capacity in the visual system damaged by aging and various diseases such as glaucoma. However, non-clinical and some clinical uses of transcorneal electrical stimulation, redlight therapy, gene-therapy, and cell replacement, among other novel technologies and techniques, appear promising to help overcome some of these hurdles. Early results indicate that indeed neuronal rejuvenation; potential regeneration and ultimate replacement of the lost RGCs and their axons, such as in glaucoma; and the reestablishment of the retina-optic nerve−brain connections may be possible. Improvement and/or partial restoration of eyesight due to ocular and neurological disease-induced visual impairment in humans may thus be possible in the near future. These aspects will be discussed in this chapter.