Background: Monocular visual loss has often been labeled "retinal migraine." Yet there is reason to believe that many such cases do not meet the criteria set out by the International Headache Society (IHS), which defines "retinal migraine" as attacks of fully reversible monocular visual disturbance associated with migraine headache and a normal neuro-ophthalmic examination between attacks.

Methods: We performed a literature search of articles mentioning "retinal migraine," "anterior visual pathway migraine," "monocular migraine," "ocular migraine," "retinal vasospasm," "transient monocular visual loss," and "retinal spreading depression" using Medline and older textbooks. We applied the IHS criteria for retinal migraine to all cases so labeled. To be included as definite retinal migraine, patients were required to have had at least two episodes of transient monocular visual loss associated with, or followed by, a headache with migrainous features.

Results: Only 16 patients with transient monocular visual loss had clinical manifestations consistent with retinal migraine. Only 5 of these patients met the IHS criteria for definite retinal migraine. No patient with permanent visual loss met the IHS criteria for retinal migraine.

Conclusions: Definite retinal migraine, as defined by the IHS criteria, is an exceedingly rare cause of transient monocular visual loss. There are no convincing reports of permanent monocular visual loss associated with migraine. Most cases of transient monocular visual loss diagnosed as retinal migraine would more properly be diagnosed as "presumed retinal vasospasm."