[Afferent pupillary disorders in postchiasmal lesions of the visual pathways]

Classically, the pupillary pathway is considered as a simple reflex arc comprising retinal ganglion cells, midbrain interneurons, oculomotor nerve and short ciliary nerves. However, there are some specialties in the construction of the pupillary pathways that have to be kept in mind when dealing with diseases involving pupillary disorders. This may help to localise lesions. Additionally, studies in patients with lesions of the retrogeniculate pathways have shown that pupillary disorders are possible even with lesions not involving the classical reflex arc. The pupil is therefore not only controlled subcortically, some components are influenced by the visual cortex. The aim of this article is to clarify various findings and terms such as relative afferent pupillary defect and pupillary hemihypokinesia.