Blood clot formation involves a cascade of reactions that results in the production of thrombin, which converts fibrinogen into fibrin. In turn, fibrin aggregates and forms a clot. Hemostasis depends on a balance between this clotting cascade and the processes that break down clots, particularly the conversion of plasminogen to plasmin and plasmin's subsequent degradation of fibrin polymers. Tranexamic acid (TXA) is an agent, first patented in 1957, that competitively inhibits plasmin generation and activity.

As a result, TXA promotes clotting and, therein, hemostasis, making it useful for controlling surgical bleeding. (See figure below.) Indeed, a 2012 meta-analysis demonstrated that administering TXA intra- or perioperatively reduces the probability of receiving a blood transfusion by one-third.

Additionally, large trials have shown that TXA does not increase the risk of thromboembolic events in patients. One study noted that there was a slightly increased incidence of seizures in patients who received TXA, though this was limited to patients who underwent open-heart surgery, which is, itself, an independent risk factor for seizures. Another study halved the dose of TXA administered to its participants, but this did not reduce seizure risk amongst the participants. Thus, the data on this adverse effect remains inconclusive, and surgeons continue using TXA for its hemostatic effects, especially in cardiac and orthopedic surgeries. Given that facial plastic surgery does not incur the same sort of blood loss as cardiac or orthopedic surgery, efforts to describe TXA use in this field have focused on its established anti-inflammatory properties in addition to hemostasis. There are reports of TXA use in rhinoplasties, face lifts, and blepharoplasties; however, such reports are scarce, with randomized, double-blinded, controlled clinical trials even more so. Only one study has examined TXA use in blepharoplasties. In that study, 34 patients were randomized to receive an injection of lidocaine mixed with either TXA or saline. The authors did not find any significant difference in post-operative parameters including size of periocular ecchymoses and patient-reported pain level. Since the only randomized controlled trial investigating TXA use in blepharoplasty involved 34 participants, the investigators aim to add to the body of knowledge on this matter.

Furthermore, the investigator's study will be structured differently from that of Sagiv et al. Firstly, the patients will serve as their own controls, since we will inject one eyelid with a solution containing TXA and another with a placebo solution. This will help reduce bias between study groups that may have existed in Sagiv et al's trial. Secondly, the investigators will follow the patients for 3 months after the procedure, which is eleven weeks longer than the duration of follow-up amongst participants in Sagiv et al's trial. This will give the investigators an even better sense of TXA's impact on patients' post-operative courses. In summary, the investigators wish to characterize TXA's hemostatic and anti-inflammatory effects in patients who undergo blepharoplasty. Since there is currently only one publication that accomplishes this, the investigators' objective is to expand knowledge in this area so that surgeons performing facial plastic procedures can optimize patients' recovery and outcomes.