New Treatment for Hyphema a Bloody Good Thing
BY WILLIAM TOWNSEND, OD
A number of conditions exist that I especially dread to see coming through the door on a Friday afternoon, or for that matter, anytime. High on that list is hyphema, a condition almost always
always caused by trauma that has potential for significant complications. Among them are angle recession, glaucoma, blood staining of the corneal endothelium and secondary hyphema. Fortunately, small hyphemas (less than 50 percent of AC depth) are less likely to develop a secondary rebleed.
The body rapidly responds to blood vessel leakage by converting prothrombin into thrombin, which then converts fibrinogen into active fibrin. Fibrin forms a scaffold on which the blood clot can build. Platelets are drawn to the blood clot, where fibrin helps them attach. Without the ability to produce clots, a person could bleed to death from a minor injury. Once clots staunch the hemorrhage, they must dissolve. Otherwise, the body retains clots indefinitely and these could dislodge and block an artery or vein.
Clot removal depends on a specific series of enzymatic reactions. Plasminogen converts to plasmin, which breaks down fibrin leading to clot dissolution.
In hyphema, premature lysis of the clot can lead to secondary hyphema. These are often worse than the initial hemorrhage and may lead to elevated pressures, posterior corneal surface staining and vision loss. Secondary hyphemas are more prevalent in young children and in individuals of African descent who have sickle cell disease or sickle cell trait.
A New Topical Solution
Numerous studies regarding the best management strategy for hyphema demonstrate the efficacy of oral aminocaproic acid (ACA) 50mg/kg PO q4h for reducing secondary hemorrhage incidence. ACA blocks the conversion of plasminogen to plasmin, delaying clot dissolution and lowering risk for secondary hyphema tenfold.
Doctors initially treated hyphema with oral ACA, which can cause side effects of nausea and vomiting. As early as 1988, Eastern Virginia Medical School researchers demonstrated that a topical preparation of ACA was as efficacious as the oral form, but without the unpleasant side effects. Topical ACA isn't commercially available, but practitioners can obtain a 30 percent solution from sources such as Leiter's Compounding Pharmacy.
ACA may soon be commercially available in topical form. Ista Pharmaceutical obtained the rights to topical ACA (Caprogel) from the Eastern Virginia Medical School, and the FDA has granted an orphan drug designation for topical ACA to treat hyphema. Final approval wasn't obtained at press time. This approval would be an advantage for both practitioners and patients.
The Current Treatments
For now, the standard of care for hyphema is cycloplegia of the affected eye, patching with a Fox shield or equivalent, topical steroids for inflammation and managing elevated intraocular pressure. Crouch et al (1986) showed that modified bed rest is as effective as total bed rest. The patient should elevate his head 45 degrees and keep activities to the bare minimum.
Routine use of antifibrinolytic agents for managing hyphema is debatable. Beiran et al (2002) found that there was no indication for universal ACA use, but that practitioners should prescribe it based on risk factors, etc.
Until Caprogel is available, evidence supports using compounded topical ACA for patients at high risk for developing secondary hyphema. The critical time for rebleed is day three or four, so practitioners should use the antifibrinolytic agent as early as possible in the course of managing the disease.
Dr. Townsend is in private practice in Canyon, Texas, and is an adjunct professor at UHCO. E-mail him at firstname.lastname@example.org.