Figure 1.

White thrombus in a retinal artery This phenomenon was perhaps first described by C Miller Fisher in a clinical case discussion in the New England Journal Of Medicine. I have seen it twice, when I happened to be present when patients with carotid stenosis had sudden loss of vision in one eye. Ophthalmoscopic examination revealed white thrombus, about the color of white bread, oozing gradually through the retinal artery; when the thrombus clears, vision returns; this often happens in quadrants or hemifields of the monocular vision as branches of the retinal artery clear sequentially. (Reproduced by permission of Vanderbilt University Press from: Spence J.D. How to Prevent Your Stroke. Vanderbilt University Press, 2006.)