Retinal Migraine Affects Only One Eye at a Time
Retinal migraine, by definition, causes visual symptoms in only one eye (monocular) during each attack—it does not affect both eyes simultaneously. 1
Key Diagnostic Features
The defining characteristic of retinal migraine is monocular visual disturbance, which means the visual symptoms occur in one eye only during an attack 1, 2. The International Classification of Headache Disorders (ICHD-3) specifically defines retinal migraine as "recurrent attacks of monocular visual disturbances, including flashes, scotomas or blindness" 2.
Important Clinical Distinctions
- Retinal migraine = monocular (one eye): The visual symptoms are confined to one eye during each episode 1, 3
- Typical migraine with visual aura = binocular (both eyes): When patients experience visual aura affecting both eyes simultaneously, this represents typical migraine with aura, not retinal migraine 1
Pattern of Eye Involvement
While retinal migraine affects only one eye per attack, different attacks can affect different eyes 4. A case report describes a patient who experienced episodes affecting "either eye" over a 6-year period, but each individual episode was monocular 4.
Critical Diagnostic Pitfall
Most cases labeled as "retinal migraine" are actually not retinal migraine. Research shows that when strict ICHD criteria are applied, only 5 out of numerous reported cases actually met the definition for definite retinal migraine 5. Many cases of transient monocular visual loss are more appropriately diagnosed as "presumed retinal vasospasm" or other conditions 5.
What to Look For
During each attack, patients typically experience:
- Photopsia (flashes of light) in one eye
- Scotomas (blind spots) in one eye
- Partial or complete visual loss in one eye
- Symptoms lasting less than 1 hour 6
- Headache with migrainous features accompanying or following within 60 minutes 2
Retinal migraine is a diagnosis of exclusion—other causes of transient monocular visual loss (embolic disease, vasculitis, giant cell arteritis, retinal vascular occlusion) must be ruled out before making this diagnosis 3.