Background Managements of optic neuritis (ON) included high-dose corticosteroids or combined with systemic immunomodulatory agents. It was important to make a correct diagnosis of ON before initiation of treatment. The purpose of the study was to report and analyze the clinical features of retinal diseases in patients who were misdiagnosed as having retrobulbar ON. Methods Retrospective review of 26 patients (38 eyes) initially diagnosed with retrobulbar ON but were ultimately diagnosed with retinal or macular diseases. Data obtained from fundus examination, fluorescence fundus angiography (FFA), automated static perimetry, full-field electroretinogram (ffERG), multifocal electroretinogram (mfERG), and optical coherence tomography (OCT) were evaluated. Results Thirty-eight eyes of 26 patients were found to have misdiagnosis of retrobulbar ON, based on normal or slight abnormal fundus findings and abnormal visual evoked potentials (VEP). The mean age of the patients was 34 years and the correct diagnosis of the patients included acute zonal occult outer retinopathy (AZOOR, 15 eyes, 14 patients), occult macular dystrophy (OMD, 8 eyes, 4 patients), cone or cone-rod dystrophy (10 eyes, 5 patients), acute macular neuroretinopathy (AMNR, 3 eyes, 2 patients), and cancer-associated retinopathy (CAR, 2 eyes, 1 patient). Conclusion When attempting to diagnose retrobulbar ON in clinical practice, it is crucial to carry out necessary examinations of the retinal function and morphology to decrease misdiagnosis.