Sickle Cell Retinopathy - Sea Fan Neovascularization
medium
eye Ophthalmology
A 26-year-old Afro-Caribbean man with HbSC disease presents with floaters and a visual acuity of 6/9 in the right eye. Dilated peripheral fundoscopy reveals a fan-shaped tuft of fine, lacy neovascularization at the junction of perfused and non-perfused retina in the temporal periphery, as marked **A** in the diagram. Which of the following best describes the pathogenic mechanism underlying the formation of this lesion?
A. Sickled erythrocytes obstruct peripheral retinal capillaries, leading to retinal ischemia and subsequent VEGF upregulation at the perfused/non-perfused border
B. Chronic systemic hemolysis causes direct endothelial damage and loss of retinal pericyte coverage throughout the posterior pole
C. Autoimmune destruction of retinal pigment epithelium leads to loss of outer blood-retinal barrier integrity and abnormal vessel proliferation
D. Elevated intraocular pressure from sickling-induced trabecular meshwork obstruction triggers compensatory neovascularization
Explanation
Why option 1 is correct
The sea-fan neovascularization marked A is the hallmark of Stage III proliferative sickle retinopathy. The pathogenic mechanism is well-established: sickled erythrocytes occlude peripheral retinal capillaries, creating zones of retinal ischemia. This ischemic stimulus triggers upregulation of vascular endothelial growth factor (VEGF), which drives the formation of abnormal neovascular tufts specifically at the junction between perfused and non-perfused retina. This is the classic "sea-fan" appearance and represents the eye's maladaptive attempt to revascularize ischemic tissue. (AAO BCSC Retina; Goldberg Sickle Classification)
Why each distractor is wrong
Option 2: While chronic hemolysis does occur in sickle cell disease, it causes diffuse endothelial damage rather than the focal, border-zone neovascularization pattern seen in sea-fans. Pericyte loss is a feature of diabetic retinopathy, not the primary driver of sickle retinopathy.
Option 3: Sickle cell disease does not characteristically elevate intraocular pressure via trabecular obstruction (that is a feature of secondary glaucoma in advanced disease, not the primary mechanism). Neovascularization in sickle retinopathy is driven by ischemia, not pressure.
Option 4: Autoimmune RPE destruction is not a recognized mechanism in sickle retinopathy. The RPE changes seen (black sunburst) are hyperplastic responses to old hemorrhage, not primary autoimmune targets.
High-YieldNEET PG
Sea-fan neovascularization in sickle retinopathy = ischemia-driven VEGF upregulation at the perfused/non-perfused border; paradoxically commoner in HbSC and HbS-beta-thal than in homozygous HbSS.
AAO BCSC Retina; Goldberg Sickle Classification
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