Tehran University of Medical Sciences Current Journal of Neurology 2717-011X 16 3 2017 07 08 130 135 EN Mahsa Arzani Department of Neurology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran Mohammad Ali Sahraian Department of Neurology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran Hamed Rezaei Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran Department of Urology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran Abdorreza Naser-Moghadasi Department of Neurology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran 2017 02 17 2017 07 08 Background: Isolated relapsing optic neuropathy is a recurrent painful optic nerve inflammation without any sign of other demyelinating diseases such as multiple sclerosis (MS) or neuromyelitis optica (NMO) spectrum disorders, and the attacks are purely responsive to steroid therapy. Methods: Recurrent isolated optic neuritis (RION) was diagnosed in patients who presented with at least two disseminating episodes of optic neuritis, and negative clinical, para-clinical, and radiological features of the demyelinating, infiltrative and vasculitis disorders involving optic nerve. The patients were assigned into two groups, chronic recurrent isolated optic neuritis (CRION) entailing patients with steroid dependent attack of optic neuritis and RION patients without steroid dependent attack of optic neuritis. They were monitored over a median of 4.0 ± 2.5 years. Results: There were 16 women and six men with CRION and RION; with the median age of 31.7 ± 9.8 (29.3 ± 9.7 for women and 37.7 ± 7.7 for men). The women to men ratio was 2.6:1. The mean optic neuritis attack was 2.95 ± 1.32 in total. Eight patients were RION while 14 patients fulfilled CRION criteria and took long term immuno-suppressive drugs. In their follow-up, 4 out of 14 CRION cases (28.5%) showed clinical and concordant para-clinical features of NMO spectrum disorder. The analysis of demographic data showed that the average number of ON attacks in CRION patients (3.79 ± 2.32) was significantly more than the average in patients with RION (2.25 ± 0.46, P = 0.02). Conclusion: CRION is a disease which requires aggressive glucocorticoid and long-term immunosuppressive therapy to restore visual acuity. https://ijnl.tums.ac.ir/index.php/ijnl/article/view/1251 https://ijnl.tums.ac.ir/index.php/ijnl/article/download/1251/342