Optic Neuritis, Papillitis, and Neuronal Retinopathy.

THE word "neurone" in ancient Greece, in addition to signifying "nerve", also meant "a bow-string". The toughness of the optic nerve might be regarded as a vindication of this etymology. It is not uncommon to find the optic nerve reduced to a mere thread by a tumour or aneurysm at a time when vision is still intact. But the optic nerve is not, in fact, a nerve, but a tract of white matter. This, and the viability of this nerve, are preliminaries to any consideration of the optic neuropathies.