Peripheral homonymous scotomas from a cavernous angioma affecting fibers subserving the intermediate region of the striate cortex

PURPOSE: To report the case of a pure peripheral homonymous visual field defect and to delineate the representation of the visual field on the striate cortex. METHODS: Observational case report. Neuro-ophthalmologic and neuroimaging assessment of a patient with a cavernous angioma of the right parieto-occipital lobe. RESULTS: The patient had left homonymous scotomas located 40 degrees to 60 degrees from the vertical meridian. Neuroimaging indicated that the lesion was affecting the optic radiations at their termination in the intermediate portion of the striate cortex or the striate cortex itself. CONCLUSION: Homonymous field defects are typically located within 10 degrees of fixation. This patient had a peripheral homonymous field defect from damage to the intermediate striate cortex. Correlation of the neuroimaging findings in this case with the most commonly used maps of the representation of the visual field on the striate cortex suggests that none of the maps correctly predicts the location or extent of lesions that affect the intermediate portion of the cortex.