OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY REVEALS PARADOXICALLY DECREASING CHOROIDAL THICKNESS AND INCREASING BLOOD FLOW IN REMITTING VOGT–KOYANAGI–HARADA SYNDROME

Purpose: To assess changes in choroidal thickness and blood flow in active Vogt–Koyanagi–Harada syndrome and after remission using optical coherence tomography angiography. Methods: This was a prospective study of patients with active early uveitis secondary to Vogt–Koyanagi–Harada syndrome. They underwent optical coherence tomography angiography imaging twice: at baseline and after remission on treatment. 3- × 3- and 6- × 6-mm choriocapillaris slabs were used to evaluate parafoveal adjusted flow index as a marker for choroidal blood flow. Mean choroidal thickness of 3 points (subfoveally and 2 points 300 µ m parafoveally) was also measured. Results: Thirty-nine eyes of 25 patients were initially recruited. After excluding eyes with media opacity, submacular fibrosis, and choroidal neovascularization, 23 eyes of 14 patients were included. The mean follow-up period was 8.7 ± 2.5 months. Mean choroidal thickness in activity and remission was 581.65 ± 108.29 µ m and 318.34 ± 72.85 µ m respectively ( P < 0.01). Mean adjusted flow index in the 3- × 3-mm slabs activity and remission were 0.495 ± 0.027 and 0.519 ± 0.0336 ( P = 0.011), and the 6- × 6-mm slabs were 0.487 ± 0.037 and 0.517 ± 0.052 respectively ( P = 0.025). Conclusion: We demonstrate decreasing choroidal thickness with paradoxically increasing choroidal flow on optical coherence tomography angiography in remitting Vogt–Koyanagi–Harada syndrome. This may reflect inflammatory infiltrations or granulomas increasing choroidal thickness during activity and causing sluggish circulation of the choriocapillaris, and a reversal of this process with remission. These findings shed more light on the relationship between Vogt Koyanagi Harada syndrome and its underlying choroidal disturbances. Larger studies are needed to evaluate the efficacy of adjusted flow index in evaluating and predicting disease activity.