ABSTRACT
The nerve fibres of the optic radiations terminate in layer 4 of the primary visual striate cortex which is located on the medial aspect of the occipital lobe, superior and inferior to the calcarine fissure. The most anterior part of the visual cortex represents the extreme nasal periphery of the retina corresponding to the monocular temporal crescent of the visual fields. Pathologies causing unilateral and/or bilateral visual field loss include migraine, trauma, primary and secondary tumours and vascular abnormalities. Visual field loss may be caused by tumour compression of the visual cortex but visual field loss may result from surgery to remove the tumour. Unilateral lesions produce colour loss in the contralateral visual hemifield and patients are less aware of colour loss than those with achromatopsia. Optic atrophy is generally absent in patients with visual cortex lesions unless there is other pathology such as papilledema due to raised intracranial pressure.
