Retinal migraine and visual loss

Transient loss of vision associated with migraine:

• retinal migraine may present with a transient monocular loss of vision
  • retinal migraines are recognized as being a distinct entity within the International Headache Society's diagnostic scheme (1)
    • defined by the occurrence of at least two attacks of monocular scotoma or blindness lasting less than 1 hour and associated with headache within 1 hour of the event, occurring in the absence of ocular or structural vascular disorder
    • retinal migraine is synonymous with such terms as "ophthalmical migraine," "ocular migraine," and "headache with monocular blindness"
    • commonly seen in adults and young children
    • probably occurs as a result of vasospasm of choroidal or retinal arteries (2)
    • retinal artery ischaemia has a similar symptomatology to amaurosis fugax (2)
    • choroidal ischaemia gives symptoms of a 'jigsaw' or 'mosaic' pattern of scotoma - these enlarge to produce a total visual loss
    • choroidal artery pattern of loss is more common than the retinal pattern
    • a family history or personal history of migraine is common (2)
      • approximately 25% of sufferers of retinal migraine are thought to have a positive family history (3)
    • episodes are limited to the same eye in about 90% of cases
    • precipitating factors include postural changes, exercise (hyperventilation may cause alkalosis precipitating vascular spams), and oral contraceptive agents
    • specialist review is required to rule out other causes of sudden visual loss:
      • a range of investigations may be undertaken carotid duplex ultrasound, fluorescein angiography, CT angiography, hypercoagulability screen and ESR

Reference:

1. Headache Classification Committee of the International Headache Society (IHS). The international classification of headache disorders, 3rd edition. Cephalalgia 2018; 38: 1-211
2. Pulse (2004); 64 (24): 80.
3. Lewinshtein D et al. Familial retinal migraines. Pediatr Neurol. 2004 May;30(5):356-7.