retrochiasmal lesion
Pathology affecting the visual pathway posterior to the optic chiasm, typically producing homonymous visual field defects.
Full Definition
Retrochiasmal lesions affect the visual pathway behind the optic chiasm, including the optic tracts, lateral geniculate nuclei, optic radiations, and visual cortex. These lesions characteristically produce homonymous visual field defects that respect the vertical meridian and affect corresponding areas of both eyes' visual fields. The specific pattern of field loss helps localize the lesion along the retrochiasmal pathway. Tract lesions produce incongruous defects with relative afferent pupillary defects, while cortical lesions typically cause congruous defects without pupillary abnormalities. Common causes include stroke, tumor, trauma, and inflammatory conditions. Unlike prechiasmal lesions, retrochiasmal pathology rarely affects visual acuity unless bilateral.
Usage
Usage note: May be hyphenated as retro-chiasmal in some texts; distinguish from postgeniculate when precision is needed.
In Context
- "The congruous left homonymous hemianopia suggested a retrochiasmal lesion in the right hemisphere." — Localization
- "MRI confirmed a retrochiasmal lesion affecting the right optic radiation." — Imaging correlation