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J.R. Gonder, J.T. Gonder, A.A. Proulx; Comparing the toxicity of indocyanine green and infracyanine green to RPE cells in culture . Invest. Ophthalmol. Vis. Sci. 2004;45(13):768.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: 1. To compare the in vitro toxicity of indocyanine green (ICG) and infracyanine green (infraCG) to cultured human RPE cells, and to determine a possible safe dose to utilize for intraoperative staining of the internal limiting membrane (ILM) during macular hole surgery. 2. To assess the toxicity of two successive ICG exposures of a known safe concentration. Methods: Cultured human RPE cells (ARPE–19, ATCC, Manassas, VA) were grown to confluence and exposed to ICG or infraCG dye of varying concentrations for exposure times of 3 and 5 minutes. Cells were also exposed to two consecutive 3 minute exposures of ICG at a concentration of 0.5mg/mL, with double saline washes in between. Following dye exposure, cell viability was measured and quantified using a well–studied mitochondrial enzyme assay (MTT assay, Sigma Chemicals). All trials were repeated a sufficient number of times to ensure statistical significance of data. Results: We found that infraCG’s in vitro toxic effect paralleled that of ICG. Using the stock solution infraCG of 2.5mg/mL, cell viability measured 48% and 35% following 3 and 5 minute exposures respectively. This was similar to that we’d established for ICG previously, with viabilities of 26% and 43% respectively at a concentration of 5mg/mL (stock concentration). Safe concentrations were not seen until a dilution of 0.5mg/mL (i.e. 1/5th the stock concentration) was achieved, with cell viabilities being in excess of 95%. Once again, this result was as seen with ICG. When RPE cells were double–stained with two consecutive ICG exposures, no measurable decrease in cell viability was detected. Conclusions: Our group has previously tested the toxicity of ICG to human RPE cells at various concentrations. In this study, the toxicity of a novel dye, infracyanine green (infraCG), was compared to that previously determined for ICG. These results suggest there is no difference in toxicity of ICG versus infraCG to cultured RPE cells using clinically relevant concentrations of dye in vitro. To enhance ILM visibility, some surgeons at our center have used two consecutive dye exposures of less than one minute each using an ICG solution of 0.5mg/mL. In this study, we exposed RPE cells to two consecutive 3 minute exposures of ICG. Cells were washed with balanced salt twice between exposures. Viability of exposed cells showed no significant difference compared to non–exposed control cells. This would appear to be a safe alternative to using high concentrations of toxic dyes to improve intraoperative ILM detection.
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