Fig. 9. Perioperative assessment of anticoagulants. Anticoagulant usage is widespread and patients do not always volunteer the information that they are taking these drugs; thus, a thorough history is mandatory. These powerful agents significantly increase subconjunctival, anterior chamber, and suprachoroidal space bleeding associated with incisional glaucoma surgery. An increasingly common problem is the combined use of ASA and vitamin E; together these drugs severely inhibit platelet function preventing formation of the platelet plug. The following guidelines are useful to decrease bleeding associated with prophylactic antithrombotic drug therapy: Drug Mechanism When to discontinue before surgery Aspirin inhibits platelet aggregation 2 weeks before surgery Vitamin E interferes with platelet adhesiveness 2 weeks before surgery Plavix inhibits platelet aggregation 2 weeks before surgery Ticlid inhibits platelet aggregation 2 weeks before surgery Aggrenox inhibits platelet aggregation 2 weeks before surgery Coumadin inhibits coagulation factors 3 to 5 days before surgery Persantine inhibits platelet adhesion not necessary Plavix = clopidogrel, Ticlid = Ticlopidine, Aggrenox = ASA and dipyridamole, Coumadin = warfarin, Persantine = dipyridamole.