The authors present two illustrative cases of acute zonal occult outer retinopathy (AZOOR) which causes acute idiopathic blind spot enlargement. The disease is characterised by sudden loss of outer retinal function associated with photopsia, with minimal or no fundoscopic changes initially and electroretinographic abnormalities affecting one or both eyes. The first case was a 21-year-old white female who presented with a scotoma and ‘shimmering lights’ in her left eye. She was treated with oral steroids with resolution of symptoms, the visual field defect and the presenting multimodal ocular imaging abnormalities. The second case was a 73-year-old white female who was referred with a longstanding bitemporal hemianopia, with no clinically significant photopsia. To the author’s knowledge, case two is the longest documented duration of bilateral, progressive and chronic idiopathic enlargement of the blind spot. These two cases show the diverse range of patients and clinical manifestations that may make the diagnosis of AZOOR difficult. AZOOR should be considered a disease of neuro-ophthalmic interest with variable clinical presentations from an acute visual field defect mimicking optic neuritis, to a (pseudo) bitemporal hemianopia mimicking a chiasm compression. The authors suggest performing a multifocal electroretinogram (mfERG) and other retinal multimodal imaging, particularly optical coherence tomography (OCT) and fundus autofluorescence, in cases of unilateral or bilateral enlarged blind spot of unknown origin.

From The clinical spectrum of acute zonal occult outer retinopathy.
Wang M, Sadaka A, Prager T, et al.
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Claire Howard

Salford Royal NHS Foundation Trust, Salford, UK.

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