|SICKLE CELL DISEASE
SIGNS AND SYMPTOMS
Ocular signs include comma-shaped vessels in the bulbar conjunctiva,
iris atrophy, iris neovascularization, dull-gray fundus appearance, retinal venous
tortuosity, nonproliferative retinal hemorrhages in the subretinal, intraretinal or
preretinal position. Further signs include black sunbursts (retinal pigment epithelial
hyperplasia secondary to deep retinal vascular occlusions), glistening refractile deposits
in the retinal periphery (hemosiderin-laden macrophages), salmon patch hemorrhages
(orange-pink-colored intraretinal hemorrhage), angioid streaks (breaks in Bruch's membrane
radiating from the optic nerve), venous occlusion, artery occlusion, peripheral
neovascularization (seafan retinopathy) with subsequent vitreous hemorrhage and tractional
Normal erythrocytes, containing normal hemoglobin, appear as flexible, pliable, biconcave discs. Erythrocytes affected by sickling disease lose their biconcave shape and their ability to efficiently move through the circulatory system. The "sickled" cells become rigid, restrict blood flow, produce clots and cause tissues to become hypoxic.
Variations in the alteration of the amino acid sequence on the globin chain produce variations in the disease's expression. The four forms of the disease are often referred to by their genotype: sickle cell trait (AS), sickle cell anemia (SS), sickle cell disease (SC) and sickle cell thalasemia (SThal).
Systemically, the sickle cell anemia variation (SS) produces the most
symptoms. With respect to the eye, the sickle cell disease mutation (SC) produces the most
effects. Overall, the sickle cell trait expression (AS) produces the fewest complications.
Other causes of peripheral neovascularization include sarcoidosis, diabetes, retinal venous occlusion, Eales' disease, leukemia and ocular ischemic syndrome. However, the characteristic sea fan frond is diagnostic of sickle retinopathy.
For patients with suspicious findings, laboratory tests for sickle cell disease include the Sickledex, Sickle Prep and plasma hemoglobin electrophoresis.
Oral carbonic anhydrase inhibitors should be avoided. They may
exacerbate the sickling of blood cells.
Other reports in this section
Eyelids & Eyelashes | Conjunctiva & Sclera | Cornea
Uvea | Vitreous & Retina | Optic Nerve & Brain | Oculosystemic Disease
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