11 Determination of the etiology of thrombocytopenia is important, as treatment of immune-mediated thrombocytopenia involves the use of glucocorticoids, which can inhibit diagnosis of underlying disease processes such as lymphoma. Secondary ocular diseases, such as glaucoma or uveitis, often follow these bleeding events. 11 Because platelets play such a vital role in primary hemostasis, a platelet deficiency can easily lead to ocular hemorrhage, including hyphema and subconjunctival, retinal, or intravitreal hemorrhage (įig 4). The prevalence and severity of ocular lesions with thrombocytopenia cases have been found to be more significant than ocular lesions associated with anemia cases. 7, 11 As is the case in humans, ophthalmic disorders are reported in cases with thrombocytopenia in small animals, especially with infectious and neoplastic diseases. 7 The most common etiologies of thrombocytopenia involve platelet destruction and include immune-mediated, sepsis-related, and drug-related thrombocytopenia as well as inflammatory and infectious causes. Thrombocytopenia is the most common cause of spontaneous bleeding in dogs and can be the result of decreased platelet production, increased platelet destruction, increased platelet consumption, and increased platelet sequestration. 8 Other possible causes of coagulopathies include neoplasia (hemangiosarcoma and lymphoma), infectious diseases, snake and insect bites, and any other condition that may cause disseminated intravascular coagulation. 8, 9 Without these factors, coagulation is severely impaired and results in multiple clinical signs related to hemorrhage, including hyphema. Anticoagulant rodenticides, known to cause deficiency in vitamin K coagulation factors (II, VII, IX, and X), are the most commonly reported rodenticide toxicities in multiple studies. In emergency cases, acquired coagulopathies from anticoagulant rodenticide intoxication are diagnosed frequently. It is important to perform a full physical examination on any patient presenting for hyphema because subtle findings of petechiae or ecchymoses may prompt further investigation of underlying systemic coagulation disorders. Petechiae present in a patient with immune-mediated thrombocytopenia. 5 This is especially important because retinal detachment can result from blunt force trauma to the eye and lead to hyphema. These cases had hyphema that inhibited ophthalmic examination beyond the iris, and ocular ultrasonography was performed to investigate other ocular abnormalities. Another study investigated traumatic hyphema in animals and found they had suffered gunshot wounds, canine bites, vehicular impacts, feline scratches, and blunt trauma from a closing door, a horse kick, a high-rise fall, and a rock thrown from a lawn mower. 6 Hyphema is generally considered to be a poor prognostic indicator in patients with proptosis, resulting in enucleation in most cases. Hyphema was the second most common ocular finding in cats presenting for ocular proptosis, and was found in some of the more severe canine cases. A study investigated traumatic ocular proptosis in 84 dogs and cats and included patients suffering from dog bites, vehicular accidents, animal fights, and unknown trauma. Protection by the bony orbit and soft tissues surrounding the eye reduces the chance of hyphema, although trauma directly in the area of the orbit or soft tissues may result in damage to the globe and uveal tissues 4, 5, 6 (įig 2). These patients may present with severe clinical signs such as skull fractures or inappropriate mentation or more inconspicuous clinical signs, such as hyphema. This review highlights the most common etiologies associated with hyphema and provides guidelines to approach hyphema both diagnostically and therapeutically.īlunt force head trauma and penetrating eye wounds are some of the most common veterinary emergencies, typically caused by vehicular accidents and animal fights. 2 Although there are many known traumatic and nontraumatic causes of hyphema, finding the underlying cause and treating the condition can still be rather difficult, especially in emergency situations. 1, 4 Severe sequelae to hyphema commonly include cataract formation, phthisis bulbi, secondary glaucoma, corneal blood staining, and posterior synechiae. Hyphema can be the result of numerous disease processes that may disrupt the blood-ocular barrier, including trauma, coagulopathies, neoplasia, infectious diseases, systemic hypertension, congenital anomalies, uveitis, retinal detachments, and immune-mediated diseases. 1, 2 The blood may be characterized in several different ways: clotted or unclotted, free or associated with fibrin or hypopyon, and by the amount of the anterior chamber volume it occupies 3 (įig 1). Hyphema, blood in the anterior chamber of the eye, usually occurs following damage to and bleeding of the retinal or uveal vasculature.
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