Chiasmal syndrome. Ophthalmological and neuro-radiological aspects.

The chiasmal syndrome has distinct ophthalmological features such as visual field loss, optic disc changes, decrease in visual acuity, ocular motor disturbances and exophthalmos. However, the pathological processes in the chiasmal region often give rise to differential diagnostic problems. Before the era of computer tomography (CT) these processes could only be visualized by means of indirect or invasive examination techniques. After introduction of computer tomography these processes could be identified much more easily. The ophthalmological findings are discussed. The most frequent causes of chiasmal syndrome are demonstrated on CT scan. The neuroradiological differential diagnosis of an enlarged sella turcica is given.