Abstract

BACKGROUND:

Optic Neuritis (ON) is one of the most common clinically isolated syndromes which develops into clinically diagnosed Multiple Sclerosis (CDMS) over time.

OBJECTIVE:

To assess the conversion rate of Iranian patients presenting with idiopathic ON to CDMS as well as monitoring potential demographic and clinical risk factors.

METHODS:

Atotal of 219 patients' medical records of idiopathic ON from March 2001 to May 2009 were reviewed. Demographic findings, ophthalmologic characteristics on admission and discharge, diagnostic approaches, type and dosage of therapy were retrospectively reviewed. A structured telephone interview was then conducted to identify patients who had subsequently been diagnosed with MS. Survival analysis was used to evaluate the cumulative probability of MS conversion and contributory risk factors.

RESULTS:

From the 219 ON patients, 109 [age 11-51, female: 81%] were followed up. Among the male gender the mean age of patients developing MS was significantly lower (P=0.01). In cox regression model, female sex (p=0.07), bilateral ON (p=0.003), MRI abnormalities (p <0.001) and high dose (5g) corticosteroid therapy (p<0.001) were identified as risk factors for the development of MS. The two and five year cumulative probability of developing MS were 27% and 45%, respectively.

CONCLUSIONS:

Idiopathic ON in Iranian patients carries higher risk of progression to MS compared to other Asian countries. MRI lesions are the strongest independent risk factor of developing CDMS. Bilateral ON, female gender and high dose corticosteroid therapy are also important factors in predicting CDMS development.