Abstract
Purpose:
Chromovitrectomy allows better visualization of transparent retinal tissues in vitreoretinal interface. However, light-induced decomposition of vital dyes may cause retinal injury during chromovitrectomy. Phototoxicity of BBG (most commonly used dye), depends on the type of light source, the intensity of illumination, the distance of the light source from the surface of the retina, and the duration of exposure. In addition, concentration of the dye as well as osmolality of medium used to compose the dye solution is likely to influence the degree of phototoxicity.<br /> <br /> Purpose of this report is to test the toxic effect of BBG (varying osmolarity as well as concentrations) on retinal pigment epithelial cells exposed to illumination generated by endo illuminator that is commonly used in vitreoretinal surgery.
Methods:
Human RPE cells (ARPE-19) cells were maintained under standard cell culture conditions. Semi-confluent cells were exposed to varying osmolar solutions [2.5, 5 and 10% glucose dissolved in hank’s balanced saline solution (HBSS)]. In addition, cells were exposed to 0.025 or 0.05% of BBG for 1,5 or 10 minutes under xenon light illumination. The light source was placed 20 mm from cells to simulate conditions used in vitreoretinal surgery. Cells exposed to HBSS at similar time points served as controls. Cell viability was quantified with WST-1 assay and .results were normalized against controls with illumination and presented as percentage of cell viability.
Results:
Cell viability was 83±2.1%, 84.6±1.8%, 88.9±5.2% at 2.5%, 5% and 10% of glucose solutions in presence of xenon light, respectively (p<0.05). Exposure to 0.05% of BBG at 2.5% glucose at 20 mm distance of xenon light illumination (10 mnts) showed 62.5±11.3% of cell viability compared to 80.9±5.4% in the absence of light illumination (p<0.05). There was no significant difference in viability between the presence or absence of light illumination upto 5 mnts. RPE viability was 58.2% (0.05mg) vs 72.9% (0.025mg) [(p<0.05)].
Conclusions:
Increase in osmolarity of BBG solution, increase in concentration of BBG and increase in exposure time to surgcial illuminator significantly affected RPE cell viability and should be considered in establishing safety parameters for the use of BBG dye in vitreoretinal surgery.