A Case of MEWDS

A 46-year-old Black woman presented to the clinic with complaints of flashes of light in her left eye for the past 4 weeks. She reported that flashes of white light had been occurring in the lower left area of her vision and that she occasionally noticed a shimmering spot that lasted around a second. Overall, there were no significant changes in her vision, and the patient denied pain OU. She reported taking fluticasone propionate and cetirizine HCl as needed and had no known medical conditions, other than seasonal allergies.

THE CASE

The patient’s distance VA through her myopic spectacle prescription (-2.75 D OD, -3.50 D OS) was 20/20 OU. Entrance testing was normal. Slit-lamp examination of the anterior segment was unremarkable OU. Her IOPs were 18 mm Hg OD and 19 mm Hg OS. Her optic nerves were flat, with distinct margins and no pallor. Her cup-to-disc ratios measured 0.30 OU. On dilated fundus examination, a large confluent area of hypopigmentation was visualized surrounding the optic nerve OS with surrounding small, round hypopigmented lesions extending into the posterior pole and a few lesions in the midperipheral retina. The macula appeared flat OU. A flat choroidal nevus 0.5 disc diameters in size was seen in the superior temporal arcade. The posterior segment OD was unremarkable.

Fundus autofluorescence (FAF) showed hyperfluorescence of the confluent area around the optic nerve and extended round lesions on biomicroscopy (Figure 1). Spectral-domain OCT (SD-OCT) of the macula revealed retinal pigment epithelium (RPE) loss, ellipsoid zone loss, and outer retinal atrophy of the left eye temporal to the optic nerve (Figure 2). Visual field testing revealed no visual defects OD with a slightly enlarged blind spot superiorly OS.

This patient was diagnosed with presumed multiple evanescent white dot syndrome (MEWDS) and was educated on the condition. She was referred to a retina specialist for a second opinion, who agreed with the diagnosis. The patient reported that no treatment was mentioned and continued following up with the retina specialist for 6 months.

FOLLOW-UP

The patient was seen a few times over the following 2 years. Most of the smaller lesions in the left eye had resolved over time, and the large area of hyperfluorescence around the optic nerve was reduced by around 30% to 40% (Figure 3).

About 2 years after the first episode, the patient returned with complaints of flashes OS. She reported no floaters OU, and her vision was stable OU. She again denied any pain or discomfort.

Her BCVA was 20/20 OU. Entrance testing was normal, and anterior slit-lamp examination was unremarkable OU. IOP was 18 mm Hg OU. Dilated fundus examination OS revealed the large confluent hypopigmentation surrounding the optic nerve OS was stable but showed new small, round hypopigmented lesions extending mainly into the superior nasal midperipheral retina (Figures 4 and 5). All findings were normal OD. OCT of the left optic nerve showed atrophy of the RPE and ellipsoid zone surrounding the nerve, with no evidence of macular edema or subretinal fluid (Figure 6). The atrophy temporal to the optic nerve appeared stable (Figure 7).

MEWDS was still the leading diagnosis, but with the recurrence, the patient was sent to a retina specialist for further testing to consider other differential diagnoses (eg, multifocal choroiditis, birdshot chorioretinopathy, serpiginous choroiditis, punctate inner choroidopathy, retrobulbar optic neuritis) or masquerading conditions (eg, syphilis or sarcoidosis).

MEWDS, IN A NUTSHELL

MEWDS is an acute, typically unilateral condition that predominately affects individuals from 20 to 50 years of age and a high percentage of women (70%-80% of cases). Symptoms include photopsias, sudden vision loss, scotomas, and dyscromatopsias.¹ Some patients may report prodrome flu-like viral symptoms before ocular findings manifest, with studies stating that this can occur in up to one-third of cases.¹ Vaccinations have also been reported to possibly trigger MEWDS episodes.² MEWDS is considered a primary choriocapillaritis/inflammatory choriocapillaropathy.³

Typical presentation includes multiple small, grayish white lesions approximately 100 µm to 200 µm in size scattered throughout the posterior pole.⁴ Tiny specks of white or orangish yellow in the foveal area create a granular appearance, which is considered pathognomonic for this condition, although it may take several days to develop. It may present with mild intraocular inflammation, such as vitritis or optic nerve edema.¹

Clinical Testing

With nonspecific symptoms and similar retinal findings, MEWDS can appear similar to other white dot syndromes. Multimodal imaging is incredibly helpful for making the diagnosis and/or monitoring progression.

• SD-OCT reveals hypertrophy of the RPE or disruption of the ellipsoid zone, which usually corresponds with symptom resolution.³
• Fundus photography can illuminate the multiple small whitish dots and granular appearance of the fovea characteristic of MEWDS.³
• FAF reveals bisretinoids of lipofuscin located in the photoreceptor outer segments as hyperfluorescent lesions.⁵
• Visual field testing provides a glimpse of a patient’s functional vision, revealing enlarged blind spots or paracentral scotomas that correlate with the areas of retinal involvement.³
• Fluorescein angiography can reveal hyperfluorescence in the involved areas during the acute phase, with staining and leakage from the optic nerve appearing more prominent during the later phase.⁶
• Indocyanine green angiography may reveal patchy hypofluorescent areas in the posterior pole and midperiphery, which are more noticeable in the late angiographic phase.

Using multimodal imaging, especially the combination of FAF, SD-OCT, and indocyanine green angiography, clinicians can now diagnose MEWDS and assess lesions for progression.³

KEEP A CLOSE EYE

Prognosis is generally good with MEWDS, with many cases having spontaneous resolution of lesions and symptoms over a period of several weeks to months. As MEWDS is self-limiting, the typical course of management is observation.