Acute zonal occult outer retinopathy presenting as optic neuritis

Abstract

Acute zonal occult outer retinopathy (AZOOR) is an outer retinal disorder characterized by the acute loss of visual functions. Herein, we report a case of AZOOR presenting features mimicking optic neuritis. A 17-year-old healthy male reported fogginess in the right eye for 2 weeks. His best-corrected visual acuity was 20/20 in both eyes. Results of a color vision test and pupillary reaction were unremarkable. Funduscopic examination revealed a subtle hyperemic disc surrounded by hyperpigmentation in the right eye. Visual field examination confirmed an enlarged blind spot in the affected eye. Fundus autofluorescence imaging revealed zonal hyperautofluorescence around the optic disc. Fluorescein angiography showed optic disc staining and a window defect in the retinal pigment epithelium. Optical coherence tomography demonstrated loss of the ellipsoid line at the corresponding hyperautofluorescent region. All these characteristics indicated a diagnosis of AZOOR. However, the prolonged P100 wave observed through visual-evoked potential examination, hyperintensity T2 signal at the retrobulbar optic nerve through magnetic resonance imaging, and mild hyperemic optic disc along with optic disc staining through fluorescein angiography resemble the characteristics of optic neuritis. Because the clinical features of AZOOR are similar to those of optic neuritis, ophthalmologists should be able to differentiate between these two diseases to achieve a timely and correct diagnosis.

Diagnosis and classification of optic neuritis

“…UNKNOWN AETIOLOGY 1 0.39 Subgroups of optic neuritis from Delphi round #1-#12 not yet included at level 2 Amiodarone 138 ANCA+ 139,140 Anti-TNF-α 141,142 Associated with malformations Syndromic AZOOR [143][144][145] Behçet's 146 Cell mediated 147,148 GFAP autoantibody [149][150][151] GQ1b autoantibody [152][153][154] Giant cell arteritis 155 IgG4 156 MDEM 157 NMDA autoantibody [158][159][160] Optico-spinal optic neuritis [161][162][163] Paranasal sinusitis [164][165][166][167][168] Appendix Figure 17: Interim Classification for Delphi Rounds 12-22. This figure was then further developed incorporating the feed-back from the experts.…”

Acute-Onset Retinal Conditions Mimicking Acute Optic Neuritis: Overview and Differential Diagnosis

“…However, some acute retinal diseases may present with symptoms (e.g., visual acuity or visual field loss) and signs (e.g., relative afferent pupillary defect and a normal or swollen optic nerve) that can mimic AON. These retinal conditions may present with subtle or no apparent changes on fundus examination [1].…”

Optic Nerve MRI T2-Hyperintensity: A Nonspecific Marker of Optic Nerve Damage

“…Results: Four hundred seventy-seven patients (698 eyes) were included [mean age 52 years (SD ±18 years); 57% women]. Of the 364 of 698 eyes with optic nerve/chiasm T2-hyperintensity without atrophy, the causes were compressive (104), inflammatory (103), multifactorial (49), glaucoma (21), normal (19), and other (68); of the 219 of 698 eyes with optic nerve/chiasm T2-hyperintensity and atrophy, the causes were compressive (57), multifactorial (40), inflammatory (38), glaucoma (33), normal (7), and other (44); of the 115 of 698 eyes with optic nerve/ chiasm atrophy without T2-hyperintensity, the causes were glaucoma (34), multifactorial (21), inflammatory (13), compressive (11), normal (10), and other (26). Thirty-six eyes with optic nerve/chiasm T2-hyperintensity or atrophy did not have evidence of optic neuropathy or retinopathy on ophthalmologic examination, and 17 eyes had clinical evidence of severe retinopathy without primary optic neuropathy.…”

“…4,5 Orbital MRI performed a few months later often shows ON T2-hyperintensity and decreased ON volume (ONatrophy) due to axonal degeneration and gliosis. However, ON T2-hyperintensity has been reported in the setting of optic neuropathies and retinal disorders of any cause, [6][7][8][9][10][11] as well as in patients without a known pathology. 12 Despite existing studies illustrating the nonspecificity of MRI ON T2-hyperintensity, many providers equate this MRI finding specifically with demyelinating optic neuritis, either acute or chronic.…”

“…4,5 Orbital MRI performed a few months later often shows ON T2-hyperintensity and decreased ON volume (ON-atrophy) due to axonal degeneration and gliosis. However, ON T2-hyperintensity has been reported in the setting of optic neuropathies and retinal disorders of any cause, 6–11 as well as in patients without a known pathology. 12…”