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Common Eye Diseases and their Management - part 9

Thuyên tắc Cholesterol có thể được nhìn thấy trong các động mạch võng mạc, đôi khi kết hợp với tắc động mạch. Này thường phát sinh từ các mảng bám atheromatous trong động mạch cảnh. Thuyên tắc vôi hóa có thể được nhìn thấy trong liên kết với các bệnh van tim và nghẽn mạch tiểu cầu hoặc fibrin cũng có thể được quan sát. | 174 Common Eye Diseases and their Management Figure 21.13. Anterior ischaemic optic neuropathy. The superior part of the disc is pale.CŨ Emboli Cholesterol emboli can be seen in the retinal arteries sometimes in association with arterial occlusion. These usually arise from atheromatous plaques in the carotid artery. Calcified emboli can be seen in association with diseased heart valves and platelet or fibrin emboli can also be observed. Ischaemic Optic Neuropathy Some elderly patients complaining of visual loss in one eye are found to have a pale swollen optic disc and sometimes evidence of branch retinal artery occlusion giving an altitudinal defect of the visual field. This appearance should suggest the possibility of temporal arteritis and an erythrocyte sedimentation rate ESR and a temporal artery biopsy should be considered as urgent investigations Figure 21.13 . However there is a group known as non-arteritic or idiopathic anterior ischaemic optic neuropathy AION which occurs in otherwise healthy individuals between 45 and 65 years of age. About one-third of these patients develop bilateral disease. In these patients retinal arterial occlusion is absent. There is no known treatment for nonarteritic AION but giant cell arteritis needs to be excluded. Anaemia When the haemoglobin concentration in the blood is abnormally low this becomes apparent in the conjunctiva and ocular fundus. The conjunctiva similar to oral mucosa is pale. The retinal vessels become pale and the difference between arteries and veins becomes less apparent. The fundus background also appears pale but this sign is dependent upon the natural pigmentation of the fundus and can be misleading. In severe cases small haemorrhages are usually seen mainly around the optic disc. The haemorrhages tend to be flame-shaped but a special feature of anaemic retinopathy is the presence of white areas in the centre of some of the haemorrhages. The haemorrhages might be due to associated low platelet counts.