Blank, fuzzy, dark, bright, or flickering area covering all or part of visual field of one eye, BUT...
Patients who insist that visual loss affected only ONE eye may actually have suffered loss to both hemifields ("homonymous hemianopia"), especially if they report that "one side of vision was blank", or that they could not read normally despite having good vision in "unaffected" eye
Patients who describe "curtain coming down" or "curtain coming up" have definitely had reduced blood flow to ONE eye
Repeated visual loss lasting no more than seconds, especially if provoked by sitting or standing, suggests papilledema
All patients should undergo ophthalmologic examination to look for papilledema, retinal platelet-fibrin or calcific embolus, retinal or optic nerve ischemia
Even if ophthalmologic exam is negative, evaluation for underlying causes must occur