![]() ![]() The vascular supply of the fovea is from the choroid, and in the occlusion of retinal vessels, it does not get hampered. Inner retinal layers are absent in mature foveola. The retinal layers present at the foveola are (from inside outwards)- the internal limiting membrane, outer nuclear layer, external limiting membrane, photoreceptor layer, and RPE. However, the foveola is devoid of the inner retinal layer. In diseases causing loss of transparency (whitening or opacification) of the inner retina, the reddish color of the vascular choroid and pigmentation of retinal pigment epithelium (RPE) is not seen through the opacified retina. The macula is characterized histologically by an area with more than one layer of ganglion cell layers, and the ganglion cell layer is thick at the macula. Other related situations causing a cherry-red spot include: ![]() Retinal whitening and a cherry-red spot are important manifestations of acute CRAO. ![]() In an extensive series of 248 eyes of 240 patients with central retinal artery occlusion, the cherry-red spot was present on the initial examination in 90% of permanent CRAO cases. Other associations of CRAO include dyslipidemia, diabetes, hypertension, smoking, and pyoderma gangrenosum. Other causes of central retinal artery occlusion include myxoma or vegetation of the cardiac valves, thrombophilic disorders, and retinal migraine. On cursory examination, an examiner might mistake cilioretinal arterial occlusion in GCA for a BRAO. However, GCA might affect the cilioretinal artery, a branch of the posterior ciliary artery. ![]() GCA involves only medium and large size arteries, not arterioles (like branch retinal arteriole). Branch retinal arterioles do not have a continuous muscular coat or internal elastic lamina. Inflammatory conditions, like giant cell arteritis (GCA), may also cause CRAO, though branch retinal arterial occlusion (BRAO) is not a common feature in GCA. The embolus usually originates from the carotid plaque and, less commonly, from the heart or the aorta. The embolus may be composed of cholesterol, fibrin-platelet, or calcium. The usual cause is an embolism, which blocks the central retinal artery. Central retinal artery occlusion (CRAO)- The characteristic presentation of this disease is sudden onset unilateral visual loss in an elderly male or female. ![]()
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