Amaurosis fugax may occur in all of the following conditions except

Amaurosis fugax It refers to a sudden, temporary and painless monocular visual loss occurring due to a transient failure of retinal circulation. Common causes of amaurosis fugax are: carotid transient ischaemic attacks (TIA), embolization of retinal circulation, papilloedema, giant cell aeritis, Raynaud's disease, migraine, as a prodromal symptom of central retinal aery or carotid aery occlusion, hypeensive retinopathy, and venous stasis retinopathy. An attack of amaurosis fugax is typically described by the patients as a cuain that descends from above or ascends from below to occupy the upper or lower halves of their visual fields. Clinical characteristics: The attack lasts for two to five minutes and resolves in the reverse pattern of progression, leaving no residual deficit. Due to brief duration of the attack, it is rarely possible to observe the fundus. When observed sholy after an attack, the fundus may either be normal or reveal signs of retinal ischemia such as retinal oedema and small superficial haemorrhages. In some cases, retinal emboli in the form of white plugs (fibrin-platelet aggregates) may be seen. Ref:- A K KHURANA; pg num:-306