Only one subject demonstrated ICG-positive cells in peripheral blood and retinal signals that altered over time.
(A) Subject 3 presented a week following new onset visual loss and distortion in the right eye. Existing RPE pigment abnormalities were visible on colour fundus images, (B) with a large pigment epithelial detachment and subretinal fluid visible on spectral-domain OCT. (C) A choroidal neovascular membrane was confirmed by fluorescein and ICG angiography, at 90 and 40 seconds post-injection respectively. (D) Optos ultra-widefield ICG imaging (802 nm excitation) confirmed regions of leakage or high signal were present only at the macula. (E) At different points timed from ICG administration, Spectralis HRA imaging demonstrated punctate signals in the ICG channel only (790 nm excitation) that altered markedly between 24 hours and day 7. (F) Enlarged region illustrating changes in signal intensity and location. (G) Flow cytometry histogram of the peripheral blood sample taken at 24 hours demonstrating ICG+ signal (green) on monocyte and granulocyte populations compared to a no-ICG control (grey). Scale bars = 200 μm unless stated.