Abstract
Purpose: :
Indocyanine green (ICG) dye is stains internal limiting membrane (ILM) and facilitate easy surgical peeling during vitreo-macular surgery. However, in presence of light illumination ICG is toxic to retinal pigment epithelial cells and leads to visual field defects. As an alternative to ICG, other vital dyes such as brilliant blue green (BBG) have been used to stain ILM. In this study, we evaluated the in vitro light induced cytotoxicity of BBG on the retinal pigment epithelial cells with a commonly used vitrectomy light source.
Methods: :
Cultured human retinal pigment epithelial cells (ARPE-19) were exposed to two different concentrations (0.25 and 0.5 mg/mL) of BBG at various time intervals (1, 5 and 15 minutes). Cytotoxic effects were analyzed in presence and absence of light illumination, after exposing the cells to a metal halide light source. The light illumination used was similar to clinical conditions at varying distances of 2cm and 3.5 cm from the cells. Intensity readings were confirmed with a light meter. Cell viability was quantified with WST-1assay and morphological variations were observed using phase contrast bright field microscopy.
Results: :
Exposure to BBG at 0.25mg/mL concentration in presence of 2 cm distance of metal halide light illumination showed 89.6±4.3% of cell viability at 1 minute time point which decreased to 83.9±10.9% at 5 min and 38.9±5.1% at 15 minutes, in comparison to the control. At 0.5 mg/mL of BBG, the observed cell viability was 93.7±2.8%, 59.6±16% and 34.7±3.5% at 1, 5 and 15 minutes exposure intervals, respectively compared to control (p<0.01). At 3.5cm distance of metal halide illumination, we noted 101.6% of cell viability at 1 minute exposure at 0.25 mg/ml of BBG which decreased to 91.5% at 5min and 86.7% at 15 minutes exposure to BBG. However, at 0.5 mg/mL, cell viability decreased 98.5%, 89.7% and 74.2% at 1, 5 and 15 minutes exposure, respectively compared to control (p<0.005). In the absence of light illumination, BBG at 0.25mg/mL concentration showed cell viability in a range of 97.5-76.8% at varying time points (1, 5 and 15 minutes) which decreased further to 94.32-55.8% at higher concentration of 0.5mg/ml at respective time points.
Conclusions: :
BBG exhibits dose dependent and time dependent cytotoxicity on retinal pigment epithelial cells, that is further exaggerated in presence of halide illumination. 0.25 mg/ml of BBG at 1 minute exposure with metal halide illumination 2 cm away results in least amount of cytotoxicity.
Keywords: macular holes • drug toxicity/drug effects • vitreoretinal surgery