High Resolution Imaging of the Outer Retina in Type 2 Acute Macular Neuroretinopathy

Purpose: To investigate the outer retinal changes in a patient with type 2 acute macular neuroretinopathy (AMN). Methods: A 35-year-old Caucasian female complaining of a unilateral blind spot was imaged using various retinal imaging modalities including clinical optical coherence tomography (OCT), OCT-angiography, fundus fluorescein angiography and adaptive optics (AO). Results: Fundus examination revealed multiple paracentral reddish-brown petaloid lesions in the symptomatic left eye, while the other eye was unremarkable. Clinical OCT showed areas of hyper-reflectance at the outer plexiform layer / outer nuclear layer complex with a disrupted inner /outer segment junction, which are characteristic features of type 2 AMN. AO imaging further revealed either shortening or absence of cone outer segments within the AMN lesions attributing to the darker features observed in the enface images from fundus photography and scanning laser ophthalmoscopy. Conclusion: The AO findings indicate that the petaloid lesions in type 2 AMN are caused by a combination of the shortening and absence of the outer segment in individual cone photoreceptors.