Clinical Reasoning: A 27-Year-Old Man With Progressive Bilateral Vision Loss Resistant to Steroid Therapy.

This case involves a 27-year-old man who presented with progressive bilateral visual impairment that initially improved with steroid therapy but subsequently worsened. The clinical problem centers on diagnosing optic nerve damage with meningeal involvement unresponsive to standard interventions. The patient's vision loss began insidiously in the right eye and later affected the left, with fundoscopy showing bilateral optic nerve atrophy. Although steroids provided temporary relief, the condition deteriorated, necessitating further investigation. MRI revealed dural thickening and enhancement near the optic canals, suggesting an infiltrative or compressive process. The diagnostic approach required considering inflammatory, compressive, and infiltrative etiologies, with a biopsy ultimately proving critical when initial treatments failed. This case underscores the importance of a stepwise diagnostic strategy and highlights the need to consider rare conditions in atypical presentations, guiding readers through the differential diagnosis.