Acute presentation of vascular disease within the orbit-a descriptive synopsis of mechanisms.

Vascular events in the orbit can present with an acute onset of symptoms, and, if untreated, raised orbital pressure and reduced arterial perfusion can lead to loss of orbital functions. Such events are commonly due to haemorrhage, but can also be due to arterio-venous shunts and very rarely arise from intraorbital vascular occlusion. The likely diagnosis is often evident on taking a thorough history and examination and in most cases, after appropriate imaging, the process can be monitored for progression. Visual failure is usually due to high pressure at the orbital apex, resulting in ischaemic optic neuropathy, and any evidence of a persistent significant visual impairment should prompt intervention.