Multiple sclerosis: rationale for early treatment.

MS often presents as acute unilateral optic neuritis (ON). While it is clear that many patients with ON suffer from a generalized disease of the central nervous system that will go on to clinically definite MS (CDMS), it is also clear that others do not. As patients become increasingly wellinformed and with the development of effective pharmacotherapy for MS, the distinction between those patients with ON who have MS and those who do not has become ever more important. Recent randomized clinical trials in patients with ON or other clinically isolated syndromes (CIS) suggestive of MS and evidence of prior subclinical demyelination on magnetic resonance imaging of the brain found that treatment with recombinant interferon-beta-1a is beneficial in reducing the development of CDMS. Ophthalmologists and other non-neurologists should refer patients with acute ON or other CIS suggestive of MS to a neurologist for MS-directed investigations.