Investigating the biocompatibility of two new heavy intraocular dyes for vitreoretinal surgery with an isolated perfused vertebrate retina organ culture model and a retinal ganglion cell line.

Background: During vitreoretinal surgery, vital dyes are used to visualize anatomical structures. Substances with a density higher than water are added to facilitate sedimentation and staining. BBG with 4% PEG (ILM Blue) and BBG with TB and 4% PEG (MBB Dual) are two new dyes. This study evaluates biocompatibility of the new dye solutions, using cell cultures and electrophysiological evaluation.
Methods: To determine cytotoxicity of ILM Blue and MBB Dual for 30, 60, 120 and 320 seconds, monolayer cultures of retinal ganglion cells (RGC5) were used. For functionality testing, bovine retinas were isolated and superfused with an oxygen-saturated nutrient solution, and the electroretinogram (ERG) was recorded. The two dye solutions were applied epiretinally for 30, 60 and 120 seconds. ERG recovery was monitored.
Results: After staining with ILM Blue, no statistical significant reduction of a- or b-wave amplitudes at the end of the wash-out was recorded. For MBB Dual, only a significant reduction of the a-wave amplitudes after 30 seconds of application at the end of the wash-out was noticed, while no statistically different changes for a- and b-wave amplitudes up to 120 seconds were noted. During the MTT assay, we noted no significant difference in cell viability after 30, 60, 120 and 320 seconds of staining with ILM blue, MBB Dual or 4% PEG in comparison to the control group (DMEM, Triton X-100 0.9% as positive control) after formazan extraction.
Conclusions: ILM Blue and MBB Dual seem to be safe for clinical use for a staining period of up to 120 seconds, probably even up to 320 seconds.