Aim To assess choroidal thickness changes associated with anterior segment recurrences in patients with Vogt–Koyanagi–Harada (VKH) disease using enhanced depth imaging optical coherence tomography (EDI-OCT).

Methods EDI-OCT images were obtained periodically from 11 patients with VKH disease (22 eyes) who were followed-up due to anterior segment recurrences. Subfoveal choroidal thickness (SCT) values at the following stages were evaluated: (1) during the remission phase, (2) 1 month before detecting the anterior recurrence, (3) during the anterior recurrence and (4) after systemic prednisolone (PSL) treatment leading to remission. In comparison with SCT values in remission as baseline, the changing ratios of SCT were statistically analysed at subsequent three stages.

Results The average of the SCT changing ratios compared with the remission phase significantly increased to 1.45±0.11 during anterior segment recurrences (p=0.00044) lacking any funduscopic signs of posterior involvement. Interestingly, the average SCT ratio 1 month before detecting the recurrence had already increased to 1.30±0.08 (p=0.002). After the PSL treatment, the ratio of SCT recovered to 0.95±0.03, which was equivalent to the remission level. However, in patients with their remission SCT values less than 240 µm, the SCT ratio did not increase significantly at any time points evaluated.

Conclusions The choroid in eyes with VKH disease thickened in association with the anterior segment recurrence, and this thickening was observed prior to the recurrence. EDI-OCT may be useful for detecting latent choroidal inflammation in VKH disease, whereas it may not for patients with the relatively thin choroid.

Trial registration number The trial registration number of the internal review board of Hokkaido University Hospital is 014-0384.