Acute Retrobulbar Optic Neuropathy as the Sole Manifestation of Subarachnoid Haemorrhage from a Ruptured Anterior Communicating Artery Aneurysm.

Anterior communicating artery aneurysm is the most common form of intracranial aneurysm and subarachnoid haemorrhage (SAH) is the common presenting feature of anterior communicating artery aneurysms. In general, patients with SAH from anterior communicating artery aneurysm present with neurological deficit. We report an interesting case of a 60-year-old man who presented with acute monocular vision loss accompanied by periorbital pain without any neurological deficit, finally diagnosed with SAH from ruptured anterior communicating artery aneurysm. Five months after immediate craniotomy with aneurysm neck clipping, his visual acuity was improved to 20/63 with a pale optic disc appearance. Acute retrobulbar optic neuropathy may be the sole manifestation of SAH from ruptured anterior communicating artery aneurysm. Unilateral decrease of visual acuity with periorbital pain, in the absence of other neurological change, may be the initial and isolated sign.