Quadrantanopie

Quadrantanopia is a type of partial visual field loss in which one quarter of the visual field is missing in each eye, typically in a congruent, or homonymous, pattern. It arises from focal damage to the retrochiasmal visual pathways—most often the optic radiations or the occipital cortex—located behind the optic chiasm. Because the lesion is post-chiasmal, the resulting field defect is usually on the same side in both eyes (contralateral to the lesion).

There are two main forms. Superior quadrantanopia, where the upper visual quadrants are lost, most commonly results from lesions of the temporal lobe affecting Meyer's loop (often described as “pie in the sky”). Inferior quadrantanopia, with loss of the lower quadrants, typically stems from parietal lobe lesions (“pie on the floor”). In both cases central vision can be preserved.

Causes include ischemic or hemorrhagic stroke, brain tumors, traumatic brain injury, demyelinating disease such as multiple sclerosis, and less commonly inflammatory or infectious processes. The onset is usually sudden with vascular causes, but gradual progression may occur with tumors.

Diagnosis relies on formal visual field testing (eg, perimetry) and neuroimaging, especially MRI, to localize the lesion. Evaluation also looks for accompanying neurological signs.

Management focuses on treating the underlying cause and addressing functional impact. Rehabilitation may include visual scanning training and, in some cases, prism devices to expand usable field. Prognosis depends on the lesion and its reversibility; some deficits may improve with treatment or neuroplastic adaptation, while others become permanent. See also homonymous hemianopia and macular sparing.