This is an interesting haematological syndrome. I would question calling the occurrence simultaneous when the vision loss was symptomatically sequential. Roughly 20% of normals have areas of absent choroidal filling in the early venous phase of the retinal circulation. These areas fill suddenly as the dye arrives in a normal manner; if there is true pathological delay such as occurs with giant cell arteritis the areas tend to fill slowly and from the edges. It can not be called pathological relative choroidal perfusion delay till the retinal circulation has reached the mid venous phase as defined by the vein being half filled with fluorescence. The most common cause for a delay from injection to the early venous phase is a mild vasovagal reaction or a reduced cardiac output in a patient with atrial fibrillation. The time from injection thus cannot be used to define choroidal perfusion delay.

Yours sincerely

Paul Beaumont