<s>[INST] context: Amaurosis fugax is sudden temporary and painless loss of vison due to transient failure of retinal circulation.
It may occur in carotid transient ischemic attack (TIA)
Amaurosis is complete loss of sight in one or both eyes, in the absence of ophthalmoscopic or other marked objective signs.
 
Amaurosis fugax
It refers to sudden, temporary and painless monocular visual loss occurring due to a transient failure of retinal circulation.
Common causes are :-
Carotid transient ischaemic attacks (TIA)
Embolization of retinal circulation
Papilledema
Giant cell arteritis
Raynaud's disease
Migraine
As a prodromal symptom of central retinal artery or carotid artery occlusion
Hypertensive retinopathy
Venous stasis retinopathy
 
Typically described by the patients as a curtain that descends from above or ascends from below to occupy the upper or lower halves of their visual fields. The attack lasts for two to five minutes and resolves in the reverse pattern of progression, leaving no residual deficit.
 
Uraemic amaurosis
 
It is sudden, bilateral, complete loss of sight occuring probably due to the effect of certain toxic materials upon the cells of the visual centre in patients suffering from acute nephritis, eclampsia of pregnancy and renal failure.It is associated with dilated pupils which generally react to light. Usually, the vision recovers in 12-48 hours. [/INST] question: Amaurosisfugax is due to - | options: A: TIA B: Tobacco C: Optic neuritis D: Papilloedema | answer: A </s>