Ocular Migraine

Ocular migraine is a loose term covering two distinct entities: migraine aura with binocular visual phenomena, and retinal (monocular) migraine, a rare disorder of fully reversible monocular scintillations, scotomata or blindness lasting 5 to 60 minutes with or without headache. The monocular form is a diagnosis of exclusion because its mimics threaten sight and life.

• Women in the second to fourth decades are mainly affected.
• Proposed mechanism is retinal or ciliary vasospasm or cortical spreading depression.
• Triggers: hunger, dehydration, bright light, exertion, heat, hormonal change, sleep disturbance.

Positive phenomena (flashing lights, shimmering scotomata) or negative phenomena (graying out, blackout) in one eye, covering and uncovering each eye confirms monocular origin.

• Attack lasts 5 to 60 minutes; headache within 60 minutes in many, ipsilateral or contralateral.
• Normal eye examination between attacks.
• Differential diagnosis: carotid dissection or stenosis with amaurosis fugax, retinal artery or vein occlusion, giant cell arteritis, optic neuritis, papilloedema, retinal detachment, vitreous traction, hyperviscosity, antiphospholipid syndrome, cardiac embolism, drug effect.
• Complications: permanent monocular visual loss from retinal artery occlusion or optic neuropathy (rare), progression to migraine with typical aura, stroke risk in the presence of other vascular risk factors.

Confirm reversibility, monocular character and exclude structural and embolic causes.

• Dilated fundus examination, visual field, intraocular pressure.
• Blood pressure, ESR and CRP (age over 50 years), full blood count, glucose, lipids, clotting screen, antiphospholipid antibodies where suspected.
• Carotid Doppler or CT angiography, echocardiography and ECG if embolic source possible.
• MRI brain where aura is atypical or prolonged.

Reassure after exclusion of vascular causes, remove triggers and offer prophylaxis for frequent attacks.

• Supportive: rest in a dim room, hydration, regular meals, regular sleep, headache and attack diary.
• Pharmacological: ibuprofen 400 to 600 mg or paracetamol 1 g at onset of headache; metoclopramide 10 mg for nausea. Avoid triptans in true retinal migraine. Prophylaxis for frequent or disabling attacks: verapamil 120 to 240 mg daily in divided doses, or amitriptyline 10 to 50 mg at night, or propranolol 40 mg twice daily increasing to 80 mg twice daily. Aspirin 75 mg daily where vascular risk is present.
• Procedures: none routinely.
• Special groups: women with aura should avoid oestrogen containing contraception; pregnancy, paracetamol for attacks and low dose aspirin or propranolol if prophylaxis is essential; avoid valproate in women of childbearing potential.
• Red flags: attack over 60 minutes, fixed deficit, age over 50 years with new symptoms, jaw claudication, scalp tenderness, headache with fever, carotid bruit, abnormal fundus.
• Follow-up: review in 4 to 6 weeks, then every 6 months while on prophylaxis, with repeat vascular risk assessment.