Abstract
The primary question at hand is how often after a first bout of isolated idiopathic optic neuritis (ON) is there progression to multiple sclerosis (MS). Dr Ebers has summarized admirably many of the problems underlying studies of this point, which studies have led to results as disparate as seven cases of MS out of eight ON cases and one case out of eight. He concludes that recurrent ON is MS, and suspects that isolated ON is also MS. Until we know the etiology, I believe we must continue with the pragmatic definition of MS as a clinical entity whose signs and symptoms indicate lesions "scattered in time and space" in the central nervous system white matter. Two optic nerves are not discrete enough to be multiple, in my view. Also, MS is a prognosis as well as a diagnosis: we predict that further dysfunction will ensue over time in