Abstract
Purpose:
Indocyanine green (ICG) is a photosensitive dye, and is used as an intravenous contrast medium to examine choroidal circulation in ophthalmology. When administrated intravenously, ICG extravasates into the choroidal stroma and accumulates within the retinal pigment epithelium-Bruch's membrane complex, and residuals for at least 24 hours in the complex. In this study, we investigated ICG phototoxicity at estimated residual concentrations after ICG angiography under fluorescent lamp illumination imitating ambient light in retinal pigment epithelial (RPE) cells.
Methods:
Human RPE cell line (ARPE-19) were incubated in a colorless medium containing 0 to 10 μg/mLICG for 24 hours in the dark or under 2000 lx illumination from a fluorescent lamp. After the culture, microscopic observation was observed and cellular damage was evaluated by measuring cell viability and cell death rate. Apoptosis and lipid peroxidization was detected by TUNEL and immunostaining of malondialdehyde (MDA) respectively in the culture incubated with 10 μg/mL ICG for 24 hours. The cells were cultured with 10 μg/mL ICG under the illumination filtered through a blue, green or red dichroic mirror blocking respective color wavelengths. After the culture, cell death was evaluated.
Results:
In the culture with 10 μg/mL ICG under illumination, the cells turned oval and number of TUNEL- and MDA-positive cells increased, while the cells cultured with ICG in the dark or without ICG under the illumination maintained flat morphology without increase of TUNEL- and MDA-positivity. Cell viability decreased and cell death rate increased in the cultures under the illumination with ICG at the concentration of 5.0 μg/mL or more, but not in culture with 2.5 μg/mL ICG. Blocking green to red color wavelengths prevented the increase of cell death in the culture with 10 μg/mL ICG under the illumination.
Conclusions:
ICG at high concentrations as just after ICG angiography had a potentially of ICG phototoxicity inducing apoptosis and lipid peroxidation by irradiation of ambient light. Blocking green to red light overlapping absorption spectra of ICG could prevent the phototoxicity.
Keywords: 670 radiation damage: light/UV •
688 retina