Altitudinal hemianopia caused by occipital infarctions. Clinical and computerized tomographic correlations

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Altitudinal homonymous hemianopia is a visual field defect affecting either the upper or lower half of the visual field in both eyes.
• Bilateral occipital lobe infarctions are known to cause severe visual deficits, including central achromatopsia and prosopagnosia.
• The calcarine fissure in the occipital lobe is crucial for visual processing, with distinct areas representing different parts of the visual field.

Observation:

• Two patients with altitudinal homonymous hemianopia resulting from bilateral occipital infarctions were analyzed.
• Clinical and computerized tomographic (CT) data were correlated to map the visual field defects to specific brain regions.
• One patient presented with a superior-field defect but remarkably preserved color vision and facial recognition.

Findings:

• The study confirmed the anatomical representation of the superior visual field in the lower bank of the calcarine fissure and the inferior visual field in the upper bank.
• The patient with superior-field hemianopia demonstrated that bilateral occipital lesions do not invariably lead to central achromatopsia or prosopagnosia.
• This case highlights the complexity of visual processing and the potential for functional sparing despite significant anatomical damage.

Implications:

• Findings challenge the classical understanding of the direct correlation between specific bilateral occipital lesion locations and the occurrence of central achromatopsia and prosopagnosia.
• Suggests potential alternative pathways or compensatory mechanisms for color vision and facial recognition in cases of occipital infarction.
• Underscores the need for nuanced interpretation of neuroimaging findings in relation to visual deficits and cognitive functions.