Thrombin, a sterile protein substance, is approved for the control of hemorrhage from accessible capillaries and small venules, as observed with standard surface incisions. Its use in maintaining hemostasis during complicated intraocular surgery is off-label because such use requires injection. Intravitreal thrombin has been used to control intraocular hemorrhage during vitrectomy. The addition of thrombin (100 U/mL) to the vitrectomy infusate significantly shortens intraocular bleeding time, and thrombin produced by DNA recombinant techniques minimizes the degree of postoperative inflammation. Thrombin causes significant ultrastructural corneal endothelial changes when human corneas are exposed to 1000 U/mL.
Fibrin sealant is a biological tissue adhesive that includes a fibrinogen component and a thrombin component, both of which are prepared from pooled human plasma. When activated by thrombin, a solution of human fibrinogen imitates the final stages of the coagulation cascade. Fibrin sealant has been used widely in ophthalmic surgeries, including as a substitute for suturing in conjunctival or corneal wound closures, in fixing conjunctival autografts during pterygium surgery, for closing or preventing corneal perforation, during amniotic membrane transplantation, and in a variety of oculoplastic surgeries. It also has the advantage of reducing the total surgical time. However, the use of fibrin sealant in ophthalmic surgery is off-label.
The tissue sealant is applied as a thin layer to ensure that it covers the entire intended application area. Preparation of this product for application must adhere to the manufacturer’s instructions. The incidence of allergic reactions is low, but anaphylactic reactions have been reported after its application.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.