Overview
- Definition
A retinopathy characterized by an acute onset of scotomas and photopsia, along with visual field defects and abnormal ERG that cannot be explained by funduscopic exam alone
- Symptoms
Sudden onset of scotomas
Photopsia
Nyctalopia or hemeralopia
- Laterality
More often unilateral on presentation, but 75% become bilateral over time (months to years)
- Course
Acute onset with a self-limiting course, but recurs in one third of cases
- Vision stabilizes over 6 months in 80% of patients
70% with visual acuity 20/40 or better
+ prognostic factors: No fundus pigmentary changes, bilateral disease, male gender
− prognostic factors: vitreous cells, fundus pigmentary changes, female gender
- Age of onset
Mid-30s
- Gender/Race
F:M = 9:1
Caucasian predominance
- Systemic associations
- 50% of patients report antecedent events
Viral illness within days to weeks of ocular symptoms
Headaches
Pregnancy
Hep B vaccination and tick bite (single cases)
30% of patients have concurrent autoimmune diseases, including hypothyroidism, Hashimoto’s thyroiditis, Graves’ disease, myasthenia gravis, multiple sclerosis, insulin-dependent diabetes mellitus, CREST syndrome, Addison’s disease, Sjögren’s syndrome, and Crohn’s disease
Exam: Ocular
Anterior Segment
Normal, except for RAPD if one eye is more affected
Posterior Segment
Often appears normal initially, with very mild pigmentary changes
Eventual fundus depigmentation ranges from mild to severe, RP-like
Attenuated retinal arterioles in affected zones
Mild vitreous cellularity (higher grade = more diffuse outer retinal damage and worse prognosis)
CNV is exceedingly rare
Imaging
- ERG
Despite being focal by appearance, AZOOR causes a global dysfunction of the cones and RPE. Full-field ERG findings are highly variable and there is no pathognomonic pattern
Reduction in amplitude and delay in the implicit time of the A and/or B wave response to photopic white light and/or 30 Hz flicker, loss of the cone component from the response to scotopic dim red light
- VF
Blindspot enlargement with or without central scotomas that may correspond with mild depigmentation on fundus examination
May mimic central lesions
- FAF
Best in delineating disease extent and monitoring for progression
Trizonal distribution: (1) normal FAF just outside of the boundary of lesion; (2) speckled hyper-FAF within lesion; (3) central hypo-AF indicative of RPE/choroidal atrophy
- OCT
Loss of ellipsoid and outer nuclear layer in acute lesions
Thinning of outer and inner nuclear layers in chronic, atrophic lesions
- FA
Usually normal, but may highlight mild RPE changes; peripapillary annular depigmentation; retinal arteriolar attenuation within the affected zones; slight peripapillary capillary and/or peripheral perivascular leakage
- ICG
Affected zones can be hypofluorescent in both early and late phases
Differential Diagnosis
Normal Fundus
Retrobulbar optic neuritis
CNS lesions
Autoimmune retinopathy
Acute macular neuroretinopathy (AMN)
Acute idiopathic blindspot enlargement syndrome (AIBES)
Ocular migraine
Abnormal Outer Retina and RPE
Acute annular outer retinopathy (AAOR)
Serpiginous choroiditis
Multiple evanescent white dot syndrome (MEWDS)
Punctate inner choroidopathy (PIC)
Multifocal choroiditis and panuveitis (MCP)
Presumed ocular histoplasmosis syndrome (POHS)
Acute posterior multifocal placoid pigment epitheliopathy (APMPPE)
Birdshot retinochoroidopathy
Diffuse unilateral subacute neuroretinitis (DUSN)
Sectoral retinitis pigmentosa
Treatment
No proven treatment
Spontaneous stabilization or improvement of vision may occur within weeks to months
Systemic corticosteroids and acyclovir/valacyclovir can be trialed if vision loss is progressive
Referral/Comanagement
None