Transient monocular visual loss

Isolated monocular visual loss as an initial manifestation of polycythemia vera

A 25-year-old man developed prolonged loss of vision in the left eye. Examination revealed that visual acuity was 20/20 in the right eye and 10/20 in the left eye, with a left relative afferent pupillary defect. Fundoscopy showed multiple cotton wool spots in the left whole retina with normal optic disc. Fluorescein angiography (FA) revealed markedly delayed arterial, venous and recirculation time in the left eye without retinal arterial or venous occlusion. Bone marrow aspirate confirmed polycythemia vera. After the patient underwent phlebotomy, his visual acuity markedly improved and cotton wool spots in the retina disappeared. On follow-up FA, delayed arterial and venous filling, and recirculation time also became normalized. This case suggests that ischemic damage of the retina due to the great viscosity of blood may be a possible mechanism of monocular visual loss in polycythemia vera. Clinicians should be aware that isolated monocular visual loss may be an initial manifestation of polycythemia vera, since if untreated, polycythemia vera carries a high risk of permanent complications due to intravascular thrombosis.

Most Cases Labeled as “Retinal Migraine” Are Not Migraine

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."