Acute Idiopathic Blind Spot Enlargement and Acute Zonal Occult Outer Retinopathy: Potential Mimics of Neuro-Ophthalmic Disease.

In 1988, William Hoyt, MD, et al described "acute idiopathic blind spot enlargement" (AIBSE) in 7 symptomatic patients who had no apparent abnormalities of the optic disc or surrounding retina. With the use of multifocal electroretinography, they showed that the scotoma was caused by occult retinal dysfunction. In 1992, J. Donald Gass, MD, described "acute zonal occult outer retinopathy" (AZOOR) in 13 patients who had sudden loss of often large zones of visual field without fundus abnormalities. Most patients developed zonal atrophy of retinal pigment epithelium and had no improvement in vision. Gass believed that AZOOR, multiple evanescent white dot syndrome, multifocal choroiditis, and AIBSE were all variants of the same disorder. Despite over 3 decades of numerous reports, the classification of these entities, their pathogenesis, and treatment remain controversial. AIBSE and AZOOR may be mistaken for an acute optic neuropathy, so it behooves the neuro-ophthalmologist to be familiar with these disorders. This review describes the initial recognition of AIBSE and its relationship to AZOOR.