Etiology and Clinical Features of Left Homonymous Hemianopia
Vascular Etiologies
- Ischemic stroke is the leading cause of left homonymous hemianopia, accounting for approximately 70 % of all cases. The majority arise from infarction in the right posterior cerebral artery (PCA) territory affecting the right occipital lobe. American College of Radiology (Level of evidence not specified). 1
- Right PCA infarction is the most frequent vascular lesion when the right occipital lobe is involved. American College of Radiology (Level of evidence not specified). 1
- Right middle cerebral artery (MCA) territory infarction can produce left hemianopia by damaging the right optic radiations. American College of Radiology (Level of evidence not specified). 1
- Cerebral venous thrombosis involving the right transverse sinus or posterior superior sagittal sinus may lead to hemorrhagic infarction of the right occipital cortex, resulting in left hemianopia. American College of Radiology (Level of evidence not specified). 1
Non‑vascular Etiologies
- Multiple sclerosis (demyelinating disease) accounts for about 1.4 % of left hemianopia cases. American College of Radiology (Level of evidence not specified). 1
- Brain tumors can involve any segment of the right retrochiasmal visual pathway—including optic tracts, lateral geniculate nucleus, optic radiations, or occipital cortex—producing left hemianopia. American College of Radiology (Level of evidence not specified). 1
Anatomical Localization
| Anatomical Site (right side) | Approximate Proportion of Cases | Typical Vascular Etiology |
|---|---|---|
| Occipital lobe (most common) | 45 %–47 % | PCA stroke |
| Optic radiations | 32 %–37 % | MCA stroke |
| Optic tract / lateral geniculate nucleus | Less common | — |
These distributions are derived from imaging series reviewed by the American College of Radiology*. (Level of evidence not specified). 1
Clinical Presentation
- Sudden onset of visual field loss strongly suggests an acute vascular event (stroke). American College of Radiology (Level of evidence not specified). 1
- Gradual, progressive visual field loss is more characteristic of neoplastic processes. American College of Radiology (Level of evidence not specified). [2] [3]
- Visual acuity is typically preserved in retrochiasmal lesions causing left hemianopia, which helps differentiate them from anterior visual‑pathway lesions. American College of Radiology (Level of evidence not specified). [1] [4]