ABSTRACT Optic neuritis is an important cause of unilateral and acute visual loss in young adults, but other differential diagnoses should be considered, especially when the disease has an atypical presentation. This report presents the case of a young woman with reduced visual acuity in her right eye, associated with optic disc edema and a relative afferent pupillary defect, that was initially misdiagnosed as optic neuritis and subsequently found to have paracentral acute middle maculopathy, possibly secondary to subtle impending central retinal vein occlusion. This case emphasizes the need to remember that retinal vascular diseases can occasionally mimic optic neuritis. Detailed anamnesis and ophthalmic examination can avoid unnecessary interventions.