Abstract
Purpose: :
To assess the light-induced cytotoxicity of Indocyanine green (ICG) using different light sources commonly used in vitreous surgery.
Methods: :
Primary cultures of porcine retinal pigment epithelium (RPE) cells were incubated with ICG solution 0.05% dissolved in glucose 5% and illuminated with a 20-Gauge surgical light source for 3 or 15 minutes. 5 light sources (Halogen, mercury vapour, xenon, and metal halide) were used. Cell viability was assessed using an MTT-assay. RPE incubated with ICG without subsequent illumination and RPE cells illuminated without prior incubation with ICG served as controls. The light-induced decomposition of ICG was analyzed by high performance liquid chromatography (HPLC).
Results: :
Illumination of RPE cells with halogen-, mercury vapour-, or xenon-light sources with or without prior incubation with ICG did not affect cell viability as compared to controls. Illumination with a metal-halide light source following incubation with ICG significantly reduced cell viability. This effect was abolished by the incorporation of a 475 nm long pass filter into the optic pathway. The HPLC analysis of the ICG solution illuminated with a metal-halide light source identified six cytotoxic ICG-decomposition products.
Conclusions: :
Most light sources commonly used in vitreous surgery appear not to cause RPE damage with or without the intraocular application of ICG. With some light sources the generation of cytotoxic ICG decomposition products is pronounced so that RPE damage can occur intraoperatively. To minimize light absorption in ICG during surgery, we recommend adding optical filters to narrow the emission spectrum of the lamps. The filters should block the short wavelengths of less than 450 nm and most of the Near Infrared.
Keywords: radiation damage: light/UV • retinal pigment epithelium