Phototoxicity of Indocyanine Green under Continuous Fluorescent Lamp Illumination and Its Prevention by Blocking Red Light on Cultured Müller Cells

Abstract

To investigate the phototoxicity of persistent indocyanine green (ICG) under continuous visible light illumination and to determine whether blocking peak absorbance wavelengths of ICG is cytoprotective. Cultured quail Müller cells were exposed to 0 to 5 mg/mL ICG for 30 seconds or 10 minutes and then were cultured in a colorless medium for 24 hours with or without continuous fluorescent lamp illumination. Cells exposed to 5 mg/mL ICG for 10 minutes were cultured under illumination filtered through a dichroic mirror that blocks red to near-infrared, green, or blue wavelengths. After microscopic observation, cell viability and cell death were evaluated. ICG exposure followed by illuminated culture induced severe morphologic changes in cells, significant reductions in cell viability, and increases in cell death from apoptosis compared with exposure to ICG or illumination alone or with no exposure. Although ICG exposure at higher concentrations caused cell damage in a dose- and time-dependent manner, an increase in cell viability was noted for cells exposed to lower ICG concentrations. Blocking red to near-infrared wavelengths prevented the decrease in cell viability and the increase in cell death in the culture exposed to ICG followed by illuminated culture. Continuous fluorescent lamp illumination enhanced the cytotoxicity of persistent ICG on Müller cells in a dose- and exposure time-dependent manner. Blocking peak absorbance wavelengths of ICG prevented photodynamic cytotoxicity of persistent ICG under continuous visible light illumination in vitro. This culture system could be used to study the mechanisms of prevention of unfavorable outcomes in ICG-assisted surgery.