Unilateral headache and loss of vision

A 45 year old man was referred to the medical team with a one week history of unilateral headache associated with nausea and photophobia. Simple analgesia proved ineffective. His symptoms were relieved only by draping a towel over his eyes and head while avoiding movement. He usually had three or four self described “migraines” a year but said “this was the worst ever” and that he felt generally unwell. On examination, he had marked epiphora in his right eye. Visual acuity was reduced to hand movements and the pupil was fixed and mid-dilated. Severe corneal oedema made funduscopy impossible. His left eye was white with visual acuity of 6/6. There was no fever or signs of meningism. Routine blood tests were unremarkable and a computed tomogram of the head was within normal limits. The patient, who is of Middle Eastern descent, was normally fit and well and did not use regular drugs. He had no ocular history and denied trauma to the eye. He did not wear glasses. ### 1 What is the most likely diagnosis? #### Short answer Acute primary angle closure glaucoma (APACG). #### Long answer The presenting symptoms of nausea, headache, and photophobia are non-specific but can be indicative of serious neurological disease that requires urgent investigation and intervention. Subarachnoid haemorrhage and meningitis both deserve consideration, as well as some of the headache syndromes such as migraine and cluster headache. Although common to many neurological conditions, the patient’s symptoms could also have an ophthalmic cause so history taking and an appropriate examination are essential. Indeed, on closer questioning it may transpire that what was initially described as a headache is actually retro-orbital or ocular pain. Failure to consider ophthalmic disease properly and to clearly …