by Noelle La Croix, DVM, Dip. ACVO
Blood in the Eye. Part 2. Secondary Systemic Disease
Hyphema is hemorrhage, or bleeding, into the anterior chamber of the eye. In the last newsletter, I discussed the main primary intraocular conditions (trauma, uveitis, cancer, and retinal detachment) which cause hyphema. This article will discuss hyphema that arises secondary to systemic disease.
The eye is often the first target organ to manifest hemorrhage in cases of systemic vascular or bleeding disorders. This is due to an extremely high blood flow within the eye when compared with other organs. This flow also increases the likelihood that uveal vasculature will contact, and possibly trap, circulating infectious agents and/or neoplastic cells. Systemic bleeding disorders are also often first detected through the clear cornea. Most owners will immediately notice blood in their pet’s eye.
Systemic bleeding diseases usually arise from platelet or coagulation factor disorders, or involve increased capillary fragility. Increased ocular capillary fragility can breakdown the blood ocular barrier (BOB) resulting in subsequent hyphema and uveitis (vascular inflammation). Some disorders that lead to this BOB breakdown include: vasculitis, hypertension, thromboembolic disease, and hyperviscosity syndromes.
Hyphema is often the result of systemic vasculitis. Vasculitis results from direct- or immune-mediated destruction of endothelial cells. Infectious diseases associated with vasculitis include: leptospirosis, Rocky Mountain spotted fever, feline infectious peritonitis, neoplasia, systemic inflammatory response syndrome (SIRS) or sepsis, hyperadrenocorticism (Cushing’s disease), and Ehlers-Danlos syndrome. The hypoxia associated with severe anemia can also cause vasculitis.
Hyphema secondary to systemic hypertension is common in older cats and dogs. Chronic systemic hypertension leads to arteriosclerosis and arterial vasospasm. These arterial disorders cause ischemia and changes in capillary permeability of vessels associated with the ocular arteries. These capillary changes can cause hyphema and even retinal detachment. Systemic hypertension is most commonly associated with renal insufficiency, hyperthyroidism, hyperadrenocorticism, hyperaldosteronism, or the growth of a pheochromocytoma. Diabetic animals may develop systemic hypertension from their overproduction of renin, and blood volume expansion associated with hyperglycemia. Thromboembolic diseases are also associated with ischemia and death of ocular capillaries, leading to hyphema.
Hyperviscosity syndromes are usually caused by an excess of serum proteins, especially globulins. Vascular endothelial cells are compromised by these diseases due to blood sludging (clumping of red blood cells) and the infiltration of excess proteins into the vascular wall. Excessive globulins are also associated with platelet and coagulation factor disorders, which can lead to hyphema. Systemic diseases associated with hyperviscosity include: multiple myeloma, lymphoma, ehrlichiosis, and chronic inflammatory disease. Hyperviscosity can also be induced by severe erythrocytosis (hemorrhagic gastroenteritis, polycythemia vera), and by erythropoietin producing neoplasms.
It is often best to assume that hyphema is secondary to systemic disease until proven otherwise. Any eye presenting with hyphema should be subjected to an ophthalmic examination including Schirmer tear testing, fluorescein staining, and tonometry. A thorough history, physical examination, and manometry can help identify underlying systemic disease. Laboratory analyses should include a complete blood count, a blood chemistry, platelet count, and urinalysis. If a systemic bleeding disorder is suspected, a coagulation panel should also be performed. Geography and/or travel history can reveal underlying infectious etiologies. The proper diagnosis of hyphema will guide the appropriate treatment of the animal and its eye.
Noelle La Croix, DVM, Dip. ACVO
Veterinary Medical Center of Long Island
75 Sunrise Highway
West Islip, New York 11795
(631) 587-0800; fax (631) 587-2006
Figure 1:Dr. La Croix and veterinary technician Francesca Rivera take the blood pressure of patient “Sugar.” Photo credit: Laura Eppig.