Figure 3. White thrombus.

White thrombus, consisting of platelet aggregates, is the target of antiplatelet therapy. I have been present on two occasions when patients had episodes of amaurosis fugax and so was able to observe by ophthalmoscopy the white thrombus oozing through the retinal arteries. As the white thrombus clears, the vision returns, sometimes in vertical or horizontal hemispheres, or in quadrants, as blood flow is restored to each main branch of the retinal artery. To the best of my knowledge, this phenomenon was first described by C. Miller Fisher; a patient who had amaurosis fugax was observed by many participants in Grand Rounds, taking turns with the ophthalmoscope. Reproduced with permission from Vanderbilt University Press [2].