Assessment of the effect of distance and duration of illumination on retinal pigment epithelial cells exposed to varying doses of Brilliant Blue Green

To assess the cytotoxicity of varying concentrations of Brilliant Blue Green (BBG) on human retinal pigment epithelial (HRPE) cells exposed to metal halide surgical endoilluminator (SE) at varying distances of illumination. HRPE (ARPE-19) were exposed to 2 concentrations (0.25 and 0.5 mg/mL) of BBG and illuminated with SE for 1, 5, and 15 min. Illumination (measured with light meter) was positioned at varying distances (1 and 2.5 cm) to mimic surgical distance of illumination. Cell viability (WST-1 assay) as well as structural changes in cells was quantified. At 1 cm distance of illumination, 0.25 mg/mL BBG decreased viability of HRPE to 89.6%±4.3%, 83.9%±10.9%, and 38.9%±5.1% of controls after 1, 5, and 15 min of exposure, respectively. Similarly, 0.5 mg/mL BBG at 1 cm distance of illumination reduced the viability of HRPE to 93.7%±2.8%, 59.6%±16%, and 34.7%±3.5% of controls. At the distance of 2.5 cm, HRPE showed improved viability; cells exposed to 0.25 mg/mL BBG maintained 98.85%±3.3%, 95.31%±7.12%, and 62.07%±3.0% of viability compared with controls after 1, 5, and 15 min of exposure. Morphometric evaluation of RPE cells showed increased width (swelling) of HRPE. BBG at its clinically used concentration (0.25 mg/mL) during vitreoretinal surgery is safe and not toxic to HRPE for up to 5 min under focal illumination (1 cm) and up to 15 min under diffuse illumination (2.5 cm) from the commonly used SE. RESULTS of our study are useful in establishing safety parameters for the use of BBG dye in vitreoretinal surgery.