Survey of risk factors for expulsive choroidal hemorrhage: case reports. Substantiation of the risk factors and their incidence.

To evaluate the interaction of risk factors for expulsive hemorrhage, we evaluated 3 cases of expulsive hemorrhage and 2 of acute intraoperative choroidal effusion that occurred at the University of Tsukuba Hospital over a 16-year-period and investigated the common findings in these 5 cases. We also selected randomly 500 cataractous cases operated at the University of Tsukuba Hospital and investigated the probabilities of risk factors for expulsive hemorrhage in these control cases. The 5 affected patients exhibited more than four risk factors of expulsive hemorrhage. The probability of more than four risk factors being involved in any cataract operation was approximately 0.33% (0.17 approximately 0.67%; 95% confidence interval). The incidence of expulsive hemorrhage at our hospital was approximately 0.2%, which is similar to the probability rate. Thus, we concluded that the development of expulsive hemorrhage was proved to be related to an accumulation of the risk factors for expulsive hemorrhage.