Description
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 blind spot enlargement and centrocaecal scotoma.
Prevalence
Rare. 80-90% 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. Routine annual review may be indicated in view of the increased risk of retinal complications.
Figure 1.
Tiny, pale intraretinal dots temporal to the macula, more apparent with image enhancement (inset). The patient had visual symptoms in the left eye including left temporal scotoma with a strobe light effect and a history of a recent virus infection. Vision was R 20/18 (6/5) and L 20/20 (6/6), and there was an extensive left sided field loss.