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Johanna Meyer, Cunea Alexander, Pia Welker, Kai Licha, Dagmar Sonntag-Bensch, Steffen Schmitz-Valckenberg, Frank G. Holz; In Vivo Imaging Of A New Indocyanine Green Nanoformulation In An Animal Model. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4991.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate a novel optimized formulation of indocyanine green (nanoICG) in an animal model.
ICG was encapsulated with the nonionic solubilizer and emulsifying agent Solutol HS15 to create nanoICG in order to improve the chemical stability and fluorescence efficacy. Using confocal scanning laser ophthalmoscopy (cSLO), in vivo reflectance and fluorescence (excitation 790 nm, emission > 820 nm) imaging was performed in Dark Agouti rats that had undergone argon laser photocoagulation induction of choroidal neovascularizations (CNV). Retinal uptake and fluorescence intensity of both conventional ICG and nanoICG were compared following intravenous injection at three different time points: day 7, 14 and 21 following laser treatment.
In vivo imaging before dye application showed ill-defined retinal lesions on day 7. Immediately following intravenous dye injection, a strong fluorescence was visible in the retinal vasculature and around the focal laser lesions. Fluorescence intensity in the retinal vasculature was higher for nanoICG compared to conventional ICG at 8 minutes after injection (day 7: p=0,06; day 14: p=0,17; day 21: p=0,05). Over time, a continuous decrease of the fluorescent signal was observed for up to 60 minutes. No fluorescent signal of either nanoICG or ICG was detectable one day after application.
This study demonstrates that encapsulated ICG can be visualized in the retinal vasculature and laser-induced CNV. Its spatio-temporal kinetics can be studied using in vivo cSLO imaging. Following expanded investigations in animal models, nanoICG may be applicable in patients with retinal and choroidal diseases for earlier and more refined diagnosis.
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