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A 22 year old male dancer presented via his optometrist following an episode of transient visual loss in his left eye. He described a slow blurring and darkening of the vision of the left eye with a similarly gradual return to normal, the whole episode lasting 10 minutes. He described similar episodes every 2–3 months for the previous 3 years with no associated migrainous aura or headache, and exercise was not a trigger. Figure 1 shows images taken before, during, and 10 minutes after his presenting episode (see figure legend for description).
(A) Left eye taken at routine optometrist appointment 1 month before presenting episode; normal appearance of disc, vessels, and macula. (B) During the episode of visual loss, constriction of both arteries and veins is seen with macular pallor and a central cherry red spot and slight disc pallor. (C) 10 minutes after the previous picture when vision according to the patient had returned to normal. Some pallor remains in the macula with a central cherry red spot but the disc and vasculature have returned to normal
Visual acuity was no perception of light when tested during the episode and had recovered to 6/9 in the affected left eye when seen 2 hours later at our ophthalmic emergency department. Aside from congenital protanomaly there were no other ocular or systemic abnormalities. On subsequent review his visual acuity had returned to 6/6 bilaterally and his fundus appearance remains normal. There was no visual field abnormality (Goldmann I2e, I4e) and haematological (including thrombophilia screen), carotid, and cardiac investigations were normal.
Comment
Retinal migraine (otherwise known as ophthalmic migraines, anterior visual pathway migraines, or ocular migraines) causes monocular visual loss for 10–20 minutes which can be associated with diffuse or unilateral headache.1 People experiencing ocular migraines often have a history of one of the more conventional forms of migraine, and exercise may precipitate the attacks.2 Vasospasm of the retinal circulation or ophthalmic artery is thought to be the cause of the amaurosis of ocular migraine.1–5 Ischaemic optic neuropathy6 and permanent arcuate scotomas3 may occur after ocular migraine and retinal vascular occlusions have been reported in conjunction with cerebral7 and ocular migraine.5,8
Retinal vasospasm may be associated with underlying systemic diseases such as SLE5 and antiphospholipid syndrome.5,9 In older patients it may be associated with giant cell arteritis, polyarteritis nodosa, and eosinophilic vasculitis.1 Other associated haematological abnormalities include low protein C and S levels and positive antinuclear antibodies.5
A relative afferent pupillary defect can be demonstrated during episodes.4,10 Retinal arterioles have been reported to constrict,1 and the fovea may become more distinct1 with surrounding macular retinal pallor4 The optic discs may be pale1,2,5 early and hyperaemic later.4,7 Early isolated constriction of veins has been reported,1,10 which may be segmental,1 as well as simultaneous constriction of arterioles and veins.2 Later engorgement of the retinal veins has been observed some hours after an attack.7 Nerve fibre bundle defects can sometimes be a late finding.3
Our case demonstrates photographically the arterial vasoconstriction of retinal migraine (fig 1), which occurred in the absence of a precipitating cause such as exercise and in the absence of a migrainous aura or headache.
Doppler studies have revealed cessation of retinal arterial flow during an exercise induced retinal migraine episode.2 A 48 year old cluster headache sufferer who underwent fluorescein angiography during an ocular migraine attack demonstrated narrowing of the retinal veins and delayed retinal artery filling during the episode with normal choroidal filling.10 Most previously published photographs have shown venous, retinal, and disc changes late in the attack, perhaps reflecting that arterial vasoconstriction occurs early during attacks and is not often photographed.2,4,10,11 Alternatively, there may be a spectrum of severity of retinal migraine manifestations, which in severe cases may result in a transient pale macular area with cherry red spot.
When considered necessary, effective treatments include propranolol,10 verapamil,5 and nifedipine.2,5 Prophylactic aspirin or nifedipine may be tried to prevent exercise induced attacks,2 and inhaled amyl nitrate can be used early in an attack to try to induce resolution.4
Acknowledgments
We thank William Templeton, Eyesite Opticians, Brighton who provided photographs.
Footnotes
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The authors have no commercial interests in any products mentioned in this article.