Optic neuritis and multiple sclerosis

To discuss recent neuro-ophthalmic advances relevant to the management of optic neuritis and multiple sclerosis.

Major advances have occurred in the fields of autoimmunity in optic neuritis, and in imaging the retinal nerve fibre layer in both optic neuritis and multiple sclerosis.

A proportion of cases of optic neuritis occur in patients who do not develop multiple sclerosis; the optic neuritis may be monophasic illness or recurrent. In many recurrent cases who also have myelitis (neuromyelitis optica) a serum antibody to aquaporin-4 water channels has been detected. It remains to be seen how many cases of recurrent non-multiple sclerosis optic neuritis without myelitis will be shown to be associated with this autoantibody. Optical coherence tomography has been shown to detect axonal loss in the retina in both recovered optic neuritis and in multiple sclerosis without a past history of optic neuritis. This is not a novel observation, but the technique may provide a quantitative measure of the loss of optic nerve axons following the acute insult in optic neuritis, and chronically in primary and secondary progressive multiple sclerosis. This is of particular interest in view of the evidence that it is axonal loss, rather than demyelination with preservation of axons, that underlies disability in multiple sclerosis.