Severe Lower Gastrointestinal Bleeding Leading to Bilateral Non-arteritic Anterior Ischemic Optic Neuropathy: A Rare Systemic Complication.

Lower gastrointestinal bleeding (LGIB) is a common clinical emergency; however, systemic complications such as bilateral non-arteritic anterior ischemic optic neuropathy (NAION) are exceedingly rare. We report the case of a 78-year-old male with a history of hypertension and hyperlipidemia who developed progressive bilateral vision loss following hospitalization for severe LGIB. His hemoglobin nadir dropped to 6.9 g/dL from a baseline of 11 g/dL, prompting transfusion with one unit of packed red blood cells. Arteritic causes were ruled out through appropriate workup. Imaging demonstrated significant carotid and vertebrobasilar atherosclerotic disease, and ophthalmologic evaluation confirmed bilateral NAION. This case highlights the potential for ischemic optic neuropathy in the setting of acute anemia and underlying vascular insufficiency. Clinicians should maintain a high index of suspicion for ischemic complications following severe gastrointestinal bleeding, particularly in high-risk patients.