MULTIPLE EVANESCENT WHITE DOT SYNDROME

Multiple evanescent white dot syndrome (MEWDS) primarily affects young adults between the ages of 20 and 45 years. There is a strong female predilection. Although typically unilateral, bilateral cases of MEWDS have been described. Spontaneous recovery usually occurs within several weeks or months. There are no known racial or hereditary associations.

Symptoms

Patients with MEWDS usually present with sudden visual alterations in one eye. Symptoms include blurred vision, temporal or paracentral scotomas, photopsia, and dyschromatopsia. A preceding viral illness is reported in approximately one third of cases.

Clinical Features

Visual acuity is variable and ranges from 20/20 to 20/400. A small degree of myopia is common. A relative afferent pupillary defect may be present. The anterior segment appears normal, without signs of inflammation. Vitreous cells are mild. The optic disc may be hyperemic or edematous. The characteristic lesions are multiple small, ill-defined white dots located at the level of the outer retina or retinal pigment epithelium (RPE). The lesions may be subtle and usually fade within the first few weeks of the disease. The fovea may have an unusual orange-yellow granularity; this granularity

may persist after resolution of the white dot lesions. Atypical findings include circumpapillary patches with or without paramacular involvement and choroidal neovascularization.

Ancillary Testing

Visual field testing often reveals enlargement of the blind spot. Other temporal and paracentral scotomas may be detected.

Fluorescein angiography demonstrates early and late hyperfluorescence of the white dots at the level of the outer retina/RPE. The optic disc may appear hyperfluorescent in the late phase of the study. Indocyanine green (ICG) angiography reveals multiple small, round hypofluorescent spots in the posterior and midperipheral fundus. The number of spots seen on ICG angiography may be more numerous than those seen clinically or with fluorescein angiography.

Electrophysiologic testing may demonstrate a reduced a-wave on the electroretinogram (ERG). The electro-oculogram (EOG) also may be abnormal. The ERG and EOG abnormalities usually normalize with resolution of symptoms.

Pathology/Pathogenesis

The cause of MEWDS is unknown. A viral etiology has been suggested. Fluorescein angiographic and electrophysiologic studies have demonstrated the involvement of the RPE and photoreceptors in MEWDS. The findings with ICG angiography suggest that MEWDS affects the choroidal circulation as well. Multiple evanescent white dot syndrome has been associated with other inflammatory conditions including acute macular neuroretinopathy and multifocal choroiditis and panuveitis.

Treatment/Prognosis

Multiple evanescent white dot syndrome resolves spontaneously without need for treatment. The prognosis is excellent, with most patients achieving normal vision and visual fields within several weeks to months. Visual field loss, photopsia, and dyschromatopsia may persist. Recurrence is unusual but has been reported. Bilateral cases with asymmetric involvement or progressive bilateral involvement have occurred, but are rare. Multiple evanescent white dot syndrome should be considered in the differential diagnosis of acute idiopathic blind spot enlargement syndrome (AIBSES). Controversy exists as to whether AIBSES is the same condition as MEWDS following resolution of the white dots.

Systemic Evaluation

No systemic evaluation is required. Multiple evanescent white dot syndrome has been described following hepatitis B vaccination, but the importance of this association is unclear.

Multiple evanescent white dot syndrome is characterized by the presence of subtle white inflammatory lesions located at the level of the retinal pigment epithelium.

Optic disc edema is common in patients with multiple evanescent white dot syndrome. If present, vitreous inflammation is usually mild.

The white dots are located in the posterior fundus. They occasionally assume a “wreath-like pattern” around the optic disc.

A peculiar orange granularity of the fovea is seen in some patients with multiple evanescent white dot syndrome. The orange granularity usually develops during the resolution phase of the condition.

This 31-year-old woman presented with photopsia and temporal visual field loss in her left eye. Ophthalmoscopic examination reveals acute multiple evanescent white dot syndrome.

A visual field study of the same patient demonstrates marked enlargement of the blind spot. This blind spot enlargement may persist for several months.

NEURORETINITIS

Neuroretinitis is more appropriately termed optic neuritis with secondary retinal involvement. A number of known disease entities can produce the clinical syndrome of unilateral visual loss, optic disc swelling, and macular star with spontaneous resolution. The term Leber’s idiopathic stellate neuroretinitis is reserved for those cases in which no specific etiologic agent has been identified.

Symptoms

The presenting symptom is blurred vision, usually in one eye. Color vision is often affected out of proportion to changes in visual acuity. Rarely, patients will complain of retrobulbar pain with eye movement. A viral prodrome has been reported in approximately 50% of cases.

Clinical Features

Visual acuity is generally between 20/40 and 20/200. Due to optic nerve involvement, an afferent pupillary defect in unilateral disease can usually be elicited. Early in the disease, optic disc edema may be mild to severe, and produces a shallow exudative detachment of the macula. As the optic nerve involvement resolves, lipid deposition occurs in the macula, producing a characteristic macular star. Focal retinochoroiditis and areas of retinal vasculitis may be seen. Vascular occlusions are less common findings.

Ancillary Testing

Fluorescein angiography demonstrates intense hyperfluorescence of the optic nerve. No leakage from the retinal vessels is seen in the macula. Visual field testing will usually be abnormal, demonstrating a cecocentral scotoma or, less commonly, a central scotoma or arcuate defect. Color vision testing will be subnormal.

Pathology/Pathogenesis

Stellate maculopathy can be caused by any disease that affects capillary permeability in the optic nerve. An exudate rich in protein and lipid leaks from deep optic nerve capillaries into the peripapillary retina and macula. With resorption of the serous component, the lipid and protein precipitate in the outer plexiform layer are engulfed by macrophages, creating the characteristic macular star.

Treatment/Prognosis

If all treatable causes of neuroretinitis have been ruled out, no treatment is indicated for Leber’s idiopathic stellate neuroretinitis. The optic nerve findings resolve spontaneously in 6 to 12 weeks, and the macular star resolves in 6 to 12 months. In some cases, optic nerve pallor or macular pigmentary changes remain. Most patients recover good visual acuity. In one study, 66% of patients regained 20/20 visual acuity.

Systemic Evaluation

Cat scratch disease is a frequent cause of neuroretinitis. All patients should undergo blood testing for IgG and IgM titers to Bartonella henselae and B quintana.

Syphilis and Lyme disease should be excluded with Venereal Disease Research Laboratories (VDRL) test, fluorescent treponemal antibody absorption (FTA-ABS) test, and Lyme titers. Other conditions that may produce these clinical findings, including systemic hypertension, diabetes mellitus, and anterior ischemic optic neuropathy, should be evaluated with a complete physical examination.

Neuroretinitis related to cat scratch disease is characterized by optic disc edema with a macular star in one eye.

Early in the disease course, optic disc edema may be present without the macular star.

Fluorescein angiography reveals optic disc hyperfluorescence related to optic disc edema. The retinal blood vessels appear normal.

The macular star is most prominent nasal to the fovea in the papillomacular bundle. The macular star results from protein and lipid deposition in the outer plexiform layer.

This pair of photographs demonstrates the natural course of cat scratch neuroretinitis. Leakage of fluid from the optic disc causes fluid extension into the fovea.

As the fluid resorbs, the macular star becomes more prominent. The star may persist for several months.