Inferior homonymous quadrantanopia as a bedside localizing clue in the emergency department

In the emergency department, rapid differentiation of monocular versus binocular visual deficits is essential for accurate neuroanatomic localization and timely evaluation of vision loss. A critical and underappreciated diagnostic pitfall exists when patients report monocular visual symptoms but physical examination reveals binocular, homonymous visual field loss. Homonymous visual field defects reliably localize pathology posterior to the optic chiasm but may be underrecognized without careful bedside visual field testing.

A 49-year-old man presented with one week of progressive binocular loss of the left inferior visual field, though he initially described his symptoms as left eye vision loss accompanied by floaters and flashes. Bedside visual field testing demonstrated a left inferior homonymous quadrantanopia, clarifying the binocular nature of the deficit and localizing pathology to the right occipital lobe. Neuroimaging revealed a hemorrhagic, heterogeneously enhancing occipital lesion concerning for a high-grade glioma. Surgical resection was performed during the same hospital admission; however, histopathology demonstrated infarcted and gliotic brain parenchyma without malignancy, consistent with resolving cerebral infarction. The patient had no additional vascular risk factors identified beyond his known medical history, and visual symptoms did slowly improve during the hospitalization.

This case highlights the diagnostic importance of bedside visual field examination in emergency neurologic localization and underscores its role in uncovering binocular field deficits even when patients report monocular symptoms. Structured visual field assessment guides appropriate workups and ensures prompt definitive care.