Abstract
Multimodal imaging techniques were performed in a patient with a newly emerged visual field defect; a missing retinal lesion on fundus examination made the diagnosis challenging but infrared imaging showed a larger area of retinal abnormality temporal to the fovea. Indocyanine green angiography (IA) showed late hypofluorescence and there was mild hyperautofluorescence which is known from acute zonal occult outer retinopathy (AZOOR). Despite normal fluorescein angiography (FA) results, a perfusion loss in the outer retinal layer was detected by OCT-A. Similar OCT-A findings were recently described in patients with acute macular neuroretinopathy (AMN). Methods. The methods included FA and IA, spectral domain optical coherence tomography (SD-OCT), near infrared imaging, and autofluorescence imaging (AF), as well as OCT-A. Patient. A 36-year-old patient who suffered from acute symptoms of photopsia and scotoma on her left eye. She had an influenza-like illness two weeks earlier. The scotoma could be verified by visual field testing. Results. The affected retinal zone showed mild fading of external limiting membrane (ELM) and a disorganisation of the ellipsoid zone (EZ) on SD-OCT. OCT-A revealed a large area of reduced perfusion in the outer retinal vascular layer. Conclusion. OCT-A can help to detect reduced capillary network in patients with visual field defects and no visible fundus changes. This case seems to have features of different occult retinal disorders such as AZOOR and AMN.
Highlights
acute zonal occult outer retinopathy (AZOOR) was initially described by Gass in 1992 as an outer retinal dysfunction that affects young Caucasian patients, more often women than men [1, 2]
OCT images show often initially fading of the ellipsoid zone (EZ), potentially due to higher reflectivity of the outer nuclear layer (ONL), and show loss of photoreceptor outer segments during the course of disease [3]
The near infrared image showed a significant demarcation line temporal to the fovea, and there was a fading of the EZ on the spectral domain optical coherence tomography (SD-OCT) (Spectralis5; Heidelberg Engineering GmbH, Heidelberg, Germany) image (Figure 4)
Summary
AZOOR was initially described by Gass in 1992 as an outer retinal dysfunction that affects young Caucasian patients, more often women than men [1, 2]. Some patients suffer from an initial episode of flu like symptoms. Slight or no fundus changes are detectable [3]. Until now it remains unclear if the retinal lesions progress due to an autoimmune process, idiopathic, or due to a viral affection [2]. AMN was initially described by Bos and Deutman in 1975 [4] They described cases of patients with red and wedgeshaped paracentral lesions [4]. Studies using OCTangiography have revealed an ischemia in the deep retinal plexus as a pathogenic mechanism [7, 8]
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