Background <p>The differential diagnosis of bilateral optic disc edema with painless vision loss poses significant challenges between idiopathic intracranial hypertension (IIH) and optic neuritis (ON). While IIH classically presents with elevated intracranial pressure (ICP), headaches, and papilledema, ON typically manifests as inflammatory optic nerve demyelination with characteristic pain on eye movement. This case illustrates the diagnostic complexity arising from overlapping features of both conditions in a patient with concurrent venous sinus stenosis, underscoring the critical role of multimodal clinical-radiological correlation and therapeutic response analysis.</p> Case presentation <p>A 42-year-old female with a BMI of 29.1&#xa0;kg/m² presented with sudden bilateral vision loss over one week. The patient had a recent cold, a history of hypertension, and had been menopausal for six months. Ophthalmic examination revealed bilateral optic disc swelling with blurred margins, and visual field tests showed diffuse damage. MRI indicated bilateral optic nerve thickening and fluid accumulation, along with a mildly elevated ICP of 270 mmH₂O. Initially, optic neuritis was suspected; however, IIH was also considered due to her elevated BMI and increased ICP. Given the rapid progression of her symptoms, the patient was started on methylprednisolone pulse therapy, leading to significant visual improvement. However, subsequent MRV and DSA revealed severe stenosis of the right transverse sinus, suggesting venous sinus stenosis as a contributing factor. The patient refused surgery and continued with corticosteroid treatment, which led to further improvement of her vision. Follow-up showed normal ICP, complete resolution of optic disc edema, and sustained visual acuity after two weeks.</p> Conclusion <p>This case highlights the challenge of diagnosing bilateral optic neuritis with co-existing elevated ICP and venous sinus stenosis. The rapid progression of symptoms and the patient’s response to high-dose corticosteroids suggests optic neuritis as the primary cause of the visual loss and optic disc swelling. Despite the presence of venous sinus stenosis, the elevated ICP likely exacerbated the stenosis rather than being its direct cause. This case underscores the need for careful differentiation between IIH and optic neuritis, especially in patients with atypical presentations, and emphasizes the importance of individualized treatment plans. The patient’s recovery after corticosteroid therapy and the resolution of optic disc edema supports the diagnosis of optic neuritis, with the potential role of venous sinus stenosis in complicating the condition.</p>