Decreased choroidal blood flow velocity in the pathogenesis of multiple evanescent white dot syndrome

On the basis of angiographic features, it is suggested that choroidal circulation disturbance may be involved in the pathogenesis of multiple evanescent white dot syndrome (MEWDS). The aim of this study is to quantitatively evaluate changes in choroidal circulation hemodynamics using laser speckle flowgraphy (LSFG) in patients with MEWDS.

Twelve eyes of 12 patients with MEWDS and 12 unaffected fellow eyes as controls were included. The macular mean blur rate (MBR), a quantitative index of relative blood flow velocity in the choroid, was measured by LSFG. Sequential changes in the average MBR values at the macula with granular changes and the lesion area with white dots were analysed. Moreover, correlations between the MRR changing rate and initial visual functions were examined.

Visual functions significantly improved 3 months after initial visit with accompanying improvements in outer retinal morphology. When compared with the baseline measurements, the MBR significantly increased at the macula of the affected eyes by 20.2 % and 13.0 % at 1 and 3 months respectively (P < 0.01 for both), while no significant change was detected in fellow eyes. Similarly, the MBR increased at the lesion area by 17.8 % and 12.0 % at 1 and 3 months respectively (P < 0.05 for both). Notably, the macular MBR elevation at 1 month was negatively correlated with both initial best-corrected visual acuity and the average threshold at the macula on Humphrey perimetry at baseline (R = -0.76, P = 0.003; R = -0.60, P = 0.03, respectively), suggesting a close link between initially reduced choroidal blood flow and functional abnormalities at the onset of MEWDS.

These results, in concert with angiographic findings, are likely to reinforce the concept of choroidal circulation impairment as a predisposing factor for MEWDS.