Signs and Symptoms
Comma sign: Comma shaped vessels in the bulbar conjunctiva is due to vascular occlusion of conjunctival vessels. Vitreoretinal traction or retinal detachment cause flashes, floaters or dark shadows. Sudden loss of vision may occur due to retinal artery occlusion, vitreous hemorrhage or retinal detachment. Intravascular occlusions may be seen in optic disc vessels. Cause
Normal adult hemoglobin A molecule comprises two α and two β globin chains associated with a heme ring. Mutation at the 6th position of the beta chain is the cause of sickle cell disease. Due to sickle cell disease, vascular occlusion may occur in the conjunctiva, iris, retina, or choroid. Retinal changes occur due to blockage of retinal blood vessels by abnormal RBCs. Diagnosis
Diagnostic Techniques
Diagnosis is conducted in a multidisciplinary manner. The diagnosis of sickle cell disease can be confirmed by cation high performance liquid chromatography, haemoglobin electrophoresis in adolescents and adults and molecular genetic diagnosis in prenatal and neonatal populations. Anterior segment signs including the conjunctival sign and iris atrophy are ocular manifestations that are strongly indicative of sickle cell disease. Early stages of sickle cell retinopathy are asymptomatic. However, retinal changes that are diagnostic of sickle cell retinopathy can be visualized using fundoscopic examinations, retinography, fluorescein angiography and coherence tomography. Ultra Widefield Fluorescein Angiography is the gold standard for diagnosis of proliferative sickle cell retinopathy. It is an invasive method that assesses both anterior and posterior segment structures. Spectral Domain Optical Coherence Tomography and Coherence Tomography Angiography are non invasive methods of diagnosing proliferative retinopathy.
Sickle cell retinopathy can be defined as retinal changes due to blood vessel damage in the eye of a person with a background of sickle cell disease. It can likely progress to loss of vision in late stages due to vitreous hemorrhage or retinal detachment. Sickle cell disease is a structural red blood cell disorder leading to consequences in multiple systems. It is characterized by chronic red blood cell destruction, vascular injury, and tissue ischemia causing damage to the brain, eyes, heart, lungs, kidneys, spleen, and musculoskeletal system.People affected by sickle cell disease are commonly of African or Asian descent. Emigration patterns towards the Western Hemisphere have led to increased numbers of persons affected by sickle cell disease in regions where it was previously uncommon. Knowledge and understanding of sickle cell disease and its management are now increasingly relevant in areas such as the European Union. At a young age, a great proportion of people living with sickle cell disease can develop retinal changes. Sickle cell disease consists of several subtypes; however, the Haemoglobin type C (HbSC) subtype carries the gravest prognosis for sickle cell retinopathy and vision changes.Regular retinal examinations can aid in early detection and treatment, thus reducing the impact of the condition and the risk of vision loss. Development and progression of sickle cell retinopathy can be favorably modified through management of the underling sickle cell disease. Treatment of the general disease can ameliorate its systemic effects. Classification
Sickle cell retinopathy can be classified based on retinal changes into non-proliferative and proliferative subtypes.