Multiple evanescent white dot syndrome (MEWDS)

This article is best viewed in a PDF Format.

View PDF

Multiple evanescent white dot syndrome is a rare, acute, unilateral, multifocal retinitis. It usually affects young women, around half of whom have recently experienced viral symptoms such as headache, low-grade fever or chills, rhinorrhoea and fatigue.

The pathogenesis of MEWDS remains to be elucidated. An immunological process is suggested by the association with recent viral illnesses, descriptions of cases occurring soon after vaccinations, and an increased frequency of HLA-B51 in affected patients. Since a large proportion of patients have been using oral contraceptive medications, the possibility of hormonal influence has also been raised.

MEWDS has been considered part of a spectrum of overlapping conditions with similar symptoms and preponderance among young women. Examples include acute macular neuroretinopathy, multiple choroiditis with panuveitis, acute idiopathic blind spot enlargement syndrome and acute zonal occult outer retinopathy. These conditions may represent variations of a single disease entity. Alternatively, the overlapping clinical features may represent common findings in diseases with entirely different etiologies.

Symptoms

Although MEWDS can affect males, the typical patient is a young female with an acute onset of blurred vision, photopsias or central scotoma in one eye, often following a viral prodrome. Bilateral eye involvement and recurrences have been described.

Signs

There are numerous, small, grey-white patches in the deep retina or retinal pigment epithelium. The fovea looks granular, with tiny white to light orange dots. Mild posterior vitreous inflammation may be present. The most common visual field defects associated with MEWDS are blind spot enlargement and centrocaecal scotoma.

Prevalence

Rare 80-90 per cent of patients with MEWDS are female, most often in the 20- to 40-year age range.

Significance

There is an excellent prognosis for complete recovery within several weeks.

Differential diagnosis

Acute posterior multifocal placoid pigment epitheliopathy Birdshot chorioretinitis.

Management

Ocular tests

With fluorescein angiography, the grey-white patches may demonstrate a cluster or wreath-like pattern of hyperflourescence. The optic nerve head also stains brightly.

Review

There is no treatment of known benefit in MEWDS. Fortunately, the disease is self-limiting in the great majority of cases. The mainstay of management is patient reassurance and review.