SAFETY TESTING OF INDOCYANINE GREEN WITH DIFFERENT SURGICAL LIGHT SOURCES AND THE PROTECTIVE EFFECT OF OPTICAL FILTERS

Purpose The purpose of this study was to assess the light-induced cytotoxicity of indocyanine green (ICG) using different light sources commonly used in macular surgery and to assess the effect of optical filters. Methods Primary cultures of porcine retinal pigment epithelium cells were incubated with 0.5 mg/mL ICG solution dissolved in 5% glucose and illuminated with a surgical light fiber for 3 or 15 minutes. Halogen, mercury vapor, xenon, and metal halide light sources were used. Cell viability was assessed using the MTT assay. Retinal pigment epithelium cells without illumination served as controls. The decomposition of ICG after illumination was analyzed by high-performance liquid chromatography. Results Illumination of retinal pigment epithelium cells with all light sources with or without previous incubation with ICG did not affect cell viability compared with controls. Cell viability was significantly reduced when the cells were not rinsed immediately after incubation. The cytotoxic effect was abolished by a 475-nm long-pass filter. The high-performance liquid chromatography analysis of the illuminated ICG solution identified six cytotoxic ICG decomposition products. Conclusion Optical filters that narrow the emission spectrum of the light sources reduce the light-induced cytotoxicity of ICG. Optical filters applied in ICG-assisted macular surgery may reduce the risk of intraoperative cell damage.