Monocular Temporal Hemianopia due to Acute Zonal Occult Outer Retinopathy.

Retinal disease may mimic an optic neuropathy since both may result in a relative afferent pupillary defect (RAPD), and retinal abnormalities may not be evident on a clinical exam. We report a case of a young woman with a monocular temporal hemianopia respecting the vertical meridian due to acute zonal occult outer retinopathy (AZOOR). This 34-year-old woman presented with a 10-day history of left eye vision loss and was found to have a visual acuity of 20/20 in both eyes, a left RAPD, and left temporal hemianopia on Humphrey 24-2 SITA-Fast visual field testing. Dilated fundus examination showed a normal-appearing optic nerve and retina in both eyes. She had already had a normal magnetic resonance imaging of the orbits with contrast and retinal disease was suspected. Optical coherence tomography showed dropout of the ellipsoid zone in the peripapillary retina, and fundus autofluorescence showed hyper-autoflourescence in the peripapillary region of the left eye. A diagnosis of AZOOR was made, and no improvement with prednisone occurred at final follow-up. This case demonstrates the importance of multimodal imaging in patients referred for optic neuropathies since retinal disease such as AZOOR can produce visual field defects characteristic of optic nerve disease.