BASICS
DESCRIPTION
• Multiple evanescent white dot syndrome (MEWDS) is an idiopathic inflammatory disease of the choroid that causes mild to moderate acute vision loss (1).
• It is usually self-limited, with recovery to normal vision within several weeks without recurrence.
• It is usually unilateral.
EPIDEMIOLOGY
Incidence
• Affect younger individuals, usually in the second to fifth decades of life
• 90% of patients are female
RISK FACTORS
50% of cases are associated with a viral prodrome.
Genetics
Possible association with HLA-B51 (2).
PATHOPHYSIOLOGY
Unclear.
ETIOLOGY
• Unknown
• It is presumed to be caused by a virus.
• Genetic predisposition combined with an environmental trigger may cause the disease.
COMMONLY ASSOCIATED CONDITIONS
Acute idiopathic blind spot enlargement syndrome (AIBES)-some feel that MEWDS and AIBES (as well as a number of other “white dot” syndromes are a spectrum of the same disease) (3).
DIAGNOSIS
HISTORY
• Sudden onset of decreased central vision in one eye
• Occasionally it may be bilateral, and may occur asynchronously
• May have central scotoma or photopsias
• May have a history of a recent viral illness
PHYSICAL EXAM
• Patients often have mild myopia
• There may be a mild afferent papillary defect
• Patients may have a mild vitreitis
• Optic disc edema
• There are ill defined small white lesions in the posterior pole at the level of the RPE/outer retina
• “Orange” foveal granularity
DIAGNOSTIC TESTS & INTERPRETATION
Lab
None usually necessary as MEWDS is a clinical diagnosis.
Imaging
Initial approach
• Fluorescein angiogram shows early hyperfluorescence with late staining in a cluster or wreath-like pattern around the macula.
• OCT shows subtle disruptions of photoreceptor inner and outer segment junction (4).
Follow-up & special considerations
• ICG is usually not needed for diagnosis.
• ICG angiography usually demonstrates more numerous hypofluorescent spots than seen on fluorescein angiography.
Diagnostic Procedures/Other
An electroretinogram (ERG) may be abnormal.
DIFFERENTIAL DIAGNOSIS
• Acute idiopathic blind spot enlargement
• Acute multifocal posterior pigment epitheliopathy (AMPPE)
• Acute macular neuroretinopathy
• Multifocal choroiditis
• Birdshot retinochoroidopathy
• Primary intraocular lymphoma may rarely appear similar to MEWDS, especially in patients >50 years old (5).
TREATMENT
MEDICATION
• Observation
• Symptoms usually resolve in 1–2 months.
ADDITIONAL TREATMENT
Issues for Referral
Consider referral to a vitreoretinal specialist.
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Monthly until symptoms resolve, then as needed.
PROGNOSIS
• Visual prognosis is good with almost all patients recovering vision >20/40.
• Recurrence is rare.
COMPLICATIONS
Choroidal neovascularization is extremely rare.
REFERENCES
1. Jampol LM, Sieving PA, Pugh D, et al. Multiple evanescent white dot syndrome. I. Clinical findings. Arch Ophthalmol 1984;102:671–674.
2. Borruat FX, Herbort CP, Spertini F, et al. HLA typing in patients with multiple evanescent white dot syndrome (MEWDS). Ocular Immunol Inflamm 1998;6:39–41.
3. Gass JD. Are acute zonal occult outer retinopathy and the white spot syndromes (AZOOR complex) specific autoimmune diseases? Am J Ophthalmol 2003;135:380–381.
4. Shah GK, Kleiner RC, Augsburger JJ, et al. Primary intraocular lymphoma seen with transient white fundus lesions simulating the multiple evanescent white dot syndrome. Arch Ophthalmol 2001;119:617–620.
5. Nguyen MH, Witkin AJ, Reichel E, et al. Microstructural abnormalities in MEWDS demonstrated by ultrahigh resolution optical coherence tomography. Retina 2007;27:414–418.
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