Case of unilateral anaemic retinopathy unmasking colorectal carcinoma

Anaemic retinopathy presents commonly with bilateral retinal haemorrhages and soft exudates. Unilateral optic disc oedema in these patients has rarely been mentioned. We report a case of an atypical presentation of anaemic retinopathy with recurrent unilateral optic disc oedema and retinal haemorrhages secondary to iron deficiency anaemia from a newly diagnosed colorectal adenocarcinoma. A man in his 70s with multiple ischaemic risk factors was referred for unilateral optic disc oedema associated with a few retinal haemorrhages. Initial diagnosis was that of impending central retinal vein occlusion. The optic disc oedema initially resolved but recurred 8 months later with worsening unilateral disc oedema, 'coin-shaped' retinal haemorrhages, Roth's spots and venous tortuosity. Full blood count showed microcytic hypochromic anaemia secondary to iron deficiency and colonoscopy revealed colorectal adenocarcinoma. The patient received blood transfusions, oral iron replacement and underwent surgical resection of the tumour. The anaemia resolved, and the fundus findings resolved as well.