Multiple evanescent white dot syndrome masquerading as atypical optic neuritis: a case report

A 23-year-old female patient of Korean ethnicity presented with ocular pain and visual field defect in her left eye for 1 week. Her best corrected visual acuity was 20/20 in her right eye and 20/30 in her left eye. Pupillary size was 3 mm for both eyes. Relative afferent pupillary defect was detected in the left eye. The color vision test was normal for both eyes. A visual field test revealed blind spot enlargement in the left eye. On fundus examination, disc swelling was found in the left eye. Other abnormalities were not found. The patient was suspected of having atypical optic neuritis. Fluorescein angiography showed hyperfluorescent spots in the posterior pole and leakage from the disc in the left eye. Orbital magnetic resonance imaging did not show any abnormal findings or enhancement. A multifocal electroretinogram showed reduced amplitude for the involved area. There were relatively hyperautofluorescent lesions outside the fovea and hypoautofluorescent fovea on the blue-light fundus autofluorescence image. En face optical coherence tomography revealed multiple hyporeflective dots at the ellipsoid zone. Swept-source optical coherence tomography showed irregular cells in the ellipsoid zone with increased outer retinal thickness. On repeated fundus examination, multiple white dots were found (vaguely). The patient was diagnosed with multiple evanescent white dot syndrome and was able to recover in 6 weeks.

Patients with multiple evanescent white dot syndrome who present with disc swelling, ocular pain, and relative afferent pupillary defect might be misdiagnosed as having optic neuritis. In atypical optic neuritis, en face optical coherence tomography, blue-light fundus autofluorescence, and swept-source optical coherence tomography can aid in the differential diagnosis.