Background <p>Optic neuritis is a frequent initial presentation of multiple sclerosis (MS). It has been suggested that optic nerve lesions on magnetic resonance imaging (MRI) should be considered as an additional lesion location for the demonstration of dissemination in space (DIS) in diagnostic criteria for MS. However, the potential value of optic nerve lesion(s) in MS diagnostic criteria has not yet been sufficiently investigated.</p> Methods <p>We prospectively included 79 patients presenting with the first clinical event suggestive of MS. All patients underwent neurological work-up, visual-evoked potential (VEP) testing, cerebrospinal fluid (CSF) analysis and contrast-enhanced MRI of the brain, spinal cord and optic nerves (ON). Patients were classified results according to the McDonald 2017 criteria, the MAGNIMS criteria and&#xa0;alternative criteria considering ON imaging findings for both DIS and dissemination in time (DIT).</p> Results <p>69 patients (87%) fulfilled DIS according to the MAGNIMS criteria, 67 patients (85%) according to McDonald 2017 and 70 patients (89%) according to the alternative diagnostic criteria. Including contrast enhancing ON lesions as an additional criterion for DIT and disregarding CSF results led to n = 9 (11%) additional patients fulfilling DIT and receiving the diagnosis MS compared to the McDonald 2017 and MAGNIMS criteria. Considering CSF findings in addition to MRI, 68 patients received the diagnosis of MS according to McDonald 2017 compared to 66 patients according to MAGNIMS and 69 patients according to the alternative criteria. Regarding VEP findings as an objective finding of optic nerve involvement, 67 patients had DIS according to MAGNIMS criteria and 71 patients had DIS according to alternative criteria.</p> Conclusions <p>Diagnostic criteria including ON lesion on MRI lead only to a slightly higher sensitivity but lower specificity regarding the diagnosis of MS.</p>