Abnormalities in the hematologic system will often have associated ocular diseases or findings. All four major components of the blood (serum, red blood cells, white blood cells, and coagulation factors) have been implicated as the underlying cause of vision loss and eye disease. The maintenance of ocular health depends upon the hematologic system.
Anemia and abnormalities of red blood cell function and morphology will lead to mild to severe ischemia within the eye. Mild ischemia will be manifested as cotton wool spots (ischemia of the nerve fiber layer), microaneurysms, and scattered hemorrhages throughout the retina. Severe ischemia will lead to neovascular proliferation and the potential for significant vision loss from extensive hemorrhage or tractional retinal detachment.
Proliferation of the white blood cells in lymphoma and leukemia will have direct (invasion in ocular tissues) and indirect (increased risk of infection due to immunosuppression) effects on the visual system. White blood cell abnormalities have been reported in the ataxia telangiectasia (telangiectatic conjunctival vessels, progressive ataxia, decreased IgA, and decreased T-cell–mediated immunity) and Chediak-Higashi (albinism and defective chemotaxis and degranulation of neutrophils) syndromes.
Abnormalities of coagulation will often have associated conjunctival and retinal hemorrhages. The retinal hemorrhages of coagulopathies are typically few in number and located in the posterior pole. Disorders of blood serum including hyperviscosity can cause retinal venous disease.
Figure 18.1 Sickle Cell Anemia— Peripheral Retinal Vasculopathy
Sickle cell anemia is a disease characterized by chronic hemolysis secondary to abnormal red blood cells. During deoxygenation, the sickle hemoglobin changes its configuration to form a filamentous structure that leaves the red blood cell rigid. There is an abnormal valine substitution in the sixth position of the β chain. Clinical manifestations include acute painful crises secondary to vaso-occlusion. More severe crises can cause significant ischemic damage to the heart, liver, and kidneys. This photograph illustrates peripheral abnormal vasculature.
Figure 18.2 Sickle Cell Anemia— Neovascularization
Sickle cell disease can lead to neovascularization of the disc, macula, and peripheral retina. Proliferation of new blood vessels in the peripheral retina is the most common location. Proliferative sickle retinopathy is classified into five stages: (a) peripheral arterial occlusion; (b) peripheral arteriolar–venular anastomoses; (c) neovascular proliferation; (d) vitreous hemorrhage; and (e) retinal detachment. In the third stage, the proliferation of new blood vessels in the periphery typically forms a C-fan configuration as seen here. Treatment of proliferative disease includes cryotherapy and laser photocoagulation.
Figure 18.3 Sickle Cell Anemia— Salmon Patch
A salmon patch is a retinal hemorrhage located in the subhyaloid space or superficial retina. It is typically located in the midperiphery and becomes an orange-red color over several days. After the hemorrhage is absorbed, there may be a schisis cavity containing refractile bodies known as iridescent spots. These iridescent spots are actually macrophages filled with iron from the degrading hemoglobin.
Figure 18.4 Sickle Cell Anemia— Sunburst
This photograph demonstrates the classic black sunburst seen in sickle cell retinopathy. The lesions are round or oval and can be as large as two disc diameters. They are dark, black, and located in the peripheral retina. They represent retinal pigment epithelium that has migrated through the Bruch membrane during a vaso-occlusive episode within the retina. Following the migration, the retinal pigment epithelium undergoes hyperplasia.