White thrombi in massive subchoroidal haemorrhage: indicators of the site of its origin and of the mechanism of its control.

Sharply circumscribed white thrombi with well developed Zahn's lines resembling the free-floating ball thrombi occurring in the auricles of the heart are demonstrated histologically at the end of ruptured ciliary arteries, causing massive subchoroidal haemorrhages in two degenerated human eyes. Not only do white thrombi in subchoroidal haemorrhages, in principle, serve as indicators for the exact location of the bleeding vessel, but their formation also allows for an understanding of the natural control of arterial bleeding in the eye.