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K V Chalam, Wenhua Li, Sankarathi Balaiya; Evaluation of Brilliant Blue Green (BBG) Toxicity on Retinal Ganglion Cells Exposed to Varying levels of Illumination with Surgical Metal Halide Endoilluminator. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5773.
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© ARVO (1962-2015); The Authors (2016-present)
In macular hole surgery, indocyanine green (ICG) is used to stain and visualize epiretinal membranes and the internal limiting membrane (ILM) to facilitate the delicate surgical removal. However, in presence of light illumination ICG is toxic to retinal ganglion 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 ganglion cells at clinically relevant distances (1 cm, 2.5cm) with a commonly used vitrectomy metal halide light source.
Retinal ganglion cells (RGC-5) were grown in the presence of 95% air and 5% CO2. Cells were exposed to two different concentrations of BBG (0.25 mg/mL and 0.5 mg/mL) in presence of halide light at 1 and 2.5 cm distances from the cell culture dishes. Cells were exposed to BBG at different time points of 1 min, 5 min and 15 min. Cells exposed to light source in the absence of BBG served as control. Intensity levels (800-1900 Fc) were standardized with light meter both at source as well as on surface of the cells. Cytotoxicity after dye exposure was analyzed using WST-1 assay. Morphological changes were observed using phase contrast bright field microscopy.
Results were normalized against cell viability rate of control (which represented 100% viability). At 0.25 mg/mL concentration, cell viabilities after 1, 5 and 15 min exposure to dye and light distance of 1 cm were 89.8±7.4%, 79.6±4.9% and 56.7±4.0% of control, respectively. At 0.5 mg/ml concentration, cell viability after 1, 5 and 15 min were 79±3.1%, 66.7±3.6% and 53.1±9.4% (p<0.05). In presence of medium illumination, at 0.25 mg/ml concentration cell viability was 104.6±3.3%, 94.4±5.9% and 73.7±4.7% after 1, 5 and 15 min of exposure, respectively. At 0.5 mg/mL concentration, cell viabilities at similar time points were 96.5 ±4.8%, 84.5±3.2% and 72.3±3.9% (P< 0.05). However, at 2.5 cm distance of higher illumination, at 0.25mg/ml cell viability was 97.5±16.4%, 96.7±15.2%, 92.4±15.2% and 98.9±12.6%, 94.8±12.4% and 82.7±15.7% at 0.5mg/ml concentration.
Surgical illuminator placed at 2.5 cm for up to 5 minutes had a superior safety profile and was not toxic to RGC independent of the intensity of illumination.
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