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. In pernicious anaemia, retinal haemorrhages and bilateral optic neuropathy that manifests as cen-trocaecal scotomas are seen. In severe cases, the optic nerves are atrophic. Anaemia secondary to blood loss can give rise to ocular hypoper-fusion, which leads to anterior ischaemic optic neuropathy. Examination of the conjunctiva is perhaps of more value or at least is certainly an easier way of assessing the haemoglobin level and this part of the examination of the eye should, of course, precede ophthalmoscopy.
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