Patients will be randomized to a treatment group or placebo. In the treatment group, aprotinin will be administered, consisting of 2 x 106 KIU as a loading dose after induction of anesthesia, 2 x 106 KIU added to the CPB circuit prime, and a continuous infusion of 5 x 105 KIU•hr–1 during surgery. The infusion will be discontinued at the end of surgery. Patients and the ophthalmologist will be unaware of the study group to which each patient belong.