Intracranial arterial calcification and ectasia in visual failure.

Calcification of the major intracranial arteries is frequently observed on computed tomography (CT), particularly in the carotid siphon, and has been implicated as a causative factor in low tension glaucoma. Ectasia of the carotid siphon has also been postulated as a possible cause of compressive optic neuropathy. 153 patients, in whom high resolution CT of the orbits and parasellar region had been performed for suspected anterior visual pathway pathology, were retrospectively reviewed. The presence and severity of calcification and ectasia of the major intracranial arteries was recorded. There was a high occurrence of carotid siphon calcification, increasing with age, and independent of sex or race. Calcification was very rare in anterior cerebral, middle cerebral and basilar arteries in all age groups. The amount and degree of ectasia also increased with advancing age, and was more frequently observed in carotid and basilar than anterior and middle cerebral arteries. There was no correlation between the degree of calcification or ectasia and ophthalmological or neurological deficit.