ObjectiveTo observe the characteristic of optical coherence tomography (OCT) and subfoveal choroidal thickness(SFCT) in patients with multiple evanescent white dot syndrome (MEWDS). MethodsThe clinical data of 10 patients (10 eyes)with MEWDS were included in the study. 10 normal subjects with matched age, gender and ocular refractive status was selected as control. The patients including 9 females (9 eyes) and 1 male (1 eye), with the average age of (27±8) years. The onset time ranged from 5 to 14 days. The patients were in acute phase if it was in 2 weeks after onset, or convalescent phase if onset was 8 weeks ago. The corrected vision, slit lamp biomicroscopy, ophthalmoscope, fundus photography, fundus fluorescein angiography, indocyanine green angiography and optical coherence tomography (OCT) were performed alone or combined in all patients. The SFCT between the acute and convalescent phases were measured using enhanced depth imaging OCT. The average follow-up was 5 months. The OCT characteristics of affected eyes between acute and convalescent phase were compared. The SFCT of the affected eyes and fellow eye were compared. ResultsThe foveal inner segment-outer segment (IS/OS) was disrupted, thin, irregular in the acute phase, and restored in the convalescent phase. The SFCT of patients in the acute phase was (239±140.7) μm, in the convalescent phase was (189.9±115.6) μm. The SFCT in the acute phase was more thicker than the convalescent phase (t=5.287, P < 0.05). The SFCT of fellow eyes in the acute phase was (214.6±127.2) μm, in the convalescent phase was (186.5±108.6) μm, the difference was significant(t=3.553, P < 0.05).The SFCT in the control subject was (155.5±83.5) μm. The SFCT in the acute phase was thicker than the control(Z=-2.117, P < 0.05). ConclusionsIn the acute phase of MEWDS, the foveal IS/OS was disrupted, thin and irregular in OCT scan. The choroid is thicker in the acute phase than in the convalescent phase in both eyes, and thicker than controls.