Sickle cell retinopathy is an ocular complication of sickle cell carrier states or sickle cell disease, a common and life-threatening hemoglobinopathy affecting 1 in every 365 children born in the United States of African origin.¹

In sickle cell disease, abnormal sickle-shaped erythrocytes cause repeated cycles of vaso-occlusion and inflammation in small blood vessels. In the eye, these microvascular insults can lead to nonproliferative and proliferative sickle cell retinopathy.²

Findings consistent with nonproliferative retinopathy include salmon patches (intraretinal hemorrhages), iridescent spots (deposition of hemosiderin and macrophages under the internal limiting membrane after hemorrhage resorption), and black sunbursts (retinal pigment epithelium migration and proliferation as a result of hemorrhage).

In proliferative sickle cell retinopathy, localized retinal ischemia may lead to upregulation of vascular growth factors, and this in turn can cause retinal neovascularization, vitreous hemorrhage, and tractional retinal detachment.

In 1971, Goldberg described five stages of proliferative sickle cell retinopathy³:

The homozygous HbSS is the most common sickle cell disease genotype. HbSS patients also have the most severe systemic complications when compared to patients with compound heterozygous conditions, such as HbSC and HbS with β-thalassemia. Interestingly, however, proliferative sickle cell retinopathy is more commonly observed in HbSC and HbS with β-thalassemia patients when compared to HbSS patients.³

Sickle cell trait (HbAS) occurs when both HbA and HbS are inherited and strictly is not a form of sickle cell disease. However, reports of sickle cell retinopathy have been published in patients with sickle cell trait who have a concomitant-associated systemic disease such as diabetes, hypertension, syphilis, tuberculosis, or sarcoidosis.⁴

Optical coherence tomography (OCT) has shown characteristic temporal macular thinning in seemingly visually asymptomatic patients with sickle cell disease (Figure 17.1).

Macular thinning has been reported to be more common in HbSS patients as compared to HbSC and HbS with β-thalassemia patients.⁵

Macular thinning has also been shown to correlate with paracentral scotomas on automated perimetry in patients with sickle cell disease.⁶

Local ischemic events including paracentral acute middle maculopathy and acute macular neuroretinopathy in sickle cell disease can present as hyperreflectivity of the middle and outer retinal layers on OCT (Figure 17.2). Ellipsoid zone disruption can also be demonstrated on OCT with acute choroidal infarction in sickle cell disease (Figure 17.3).

OCT can also demonstrate retinal thickening in the acute phase and thinning in the chronic phase when central retinal arterial/vein occlusion occurs in sickle cell disease (Figures 17.4 and 17.5).⁷ Furthermore, cystoid macular edema in central retinal vein occlusion can be monitored using OCT.⁷

Studies have shown that flow loss is more common in the temporal macula, a known watershed zone in the macular vasculature, and can localize to the superficial and deep capillary plexus in patients with sickle cell disease (Figure 17.1).⁸,⁹