Sickle Cell Retinopathy
Sickle cell anemia is the most common inherited blood disorder in the United States. The sickle cell hemoglobinopathies of greatest ocular importance are those in which mutant hemoglobins S, C, or both are inherited instead of normal hemoglobin A (see BCSC Section 2, Fundamentals and Principles of Ophthalmology). Sickle cell hemoglobinopathies are most prevalent in the black population, and affect about 10% of African Americans (Table 7-1). Thalassemia, in which the α- or β-polypeptide chain is defective, is rare but frequently causes retinopathy. Although sickling and solubility tests (sickle cell preparations) are reliable indicators of the presence of hemoglobin S and are therefore excellent for sickle cell anemia screening, these tests do not distinguish between heterozygous and homozygous states in the hemoglobinopathies. Patients who test positive on sickle cell preparations should also undergo hemoglobin electrophoresis testing.
Scott AW, Lutty GA, Goldberg MF. Hemoglobinopathies. In: Schachat AP, Wilkinson CP, Hinton DR, Sadda SR, Wiedemann P, eds. Ryan’s Retina. Vol 1. 6th ed. Philadelphia: Elsevier/Saunders; 2018:chap 60.
Nonproliferative Sickle Cell Retinopathy
The retinal changes in nonproliferative sickle cell retinopathy (NPSR) are caused by arteriolar and capillary occlusion. Anastomosis and remodeling occur in the periphery, as does the resorption of blood around the infarct. Salmon-patch hemorrhages represent areas of intraretinal hemorrhage that occur after a peripheral retinal arteriolar occlusion. Refractile spots are old, resorbed hemorrhages with hemosiderin deposition within the inner retina just beneath the internal limiting membrane (ILM) (Fig 7-1). Black “sunburst” lesions are localized areas of retinal pigment epithelial hypertrophy, hyperplasia, and pigment migration in the peripheral retina, probably caused by hemorrhage.
Table 7-1 Incidence of Sickle Cell Hemoglobinopathies in North America
Figure 7-1 Salmon-patch hemorrhage in sickle cell retinopathy. A, Peripheral fundus photograph of a patient with sickle cell disease shows a retinal hemorrhage unrelated to proliferation; instead, it is the result of infarction of the retina from a vascular occlusion—a salmon patch. B, Peripheral fundus photograph of an iridescent, or refractile, patch that represents an area of previous, now resorbed, retinal hemorrhage (salmon patch).
(Courtesy of G. Baker Hubbard III, MD.)
Occlusion of parafoveal capillaries and arterioles is one cause of decreased visual acuity in patients with sickle cell retinopathy. These changes can be detected on angiography, particularly with optical coherence tomography angiography (OCTA), and may be subtle (Fig 7-2) or catastrophic (Fig 7-3). Spontaneous occlusion of the central retinal artery may also develop in patients with sickle cell hemoglobinopathies.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.