Comparison of dyes for cataract surgery - Part 1: Cytotoxicity to corneal endothelial cells in a rabbit model

Purpose: To investigate the corneal endothelial cytotoxicity of dyes for capsule staining in cataract surgery. Setting: Department of Ophthalmology and Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan. Methods: Cultured corneal endothelial cells of New Zealand white rabbits were exposed for 1 minute to 1 of the following dyes (various concentrations): indocyanine green (ICG), methylene blue (MB), gentian violet (GV), trypan blue (TB), and fluorescein sodium (FS). The degree of cell damage was determined by in vitro staining with TB and comparison with results in a control group. The effect of longer exposure (up to 10 minutes) to ICG 0.25% was also investigated. Structural changes in corneal endothelial cells after dye exposure were evaluated by light microscopy and transmission electron microscopy (TEM). Results: Indocyanine green 0.25%, MB 0.20%, GV 0.01%, TB 0.40%, and FS 10% did not induce significant damage to corneal endothelial cells. Significant cytotoxicity was observed with the following or higher dye concentrations: ICG 0.50%, MB 0.50%, and GV 0.10%. Exposure to ICG 0.25% for 1 to 10 minutes showed a trend toward cytotoxicity after 10 minutes. On TEM, corneal endothelial cells that had been exposed to ICG 0.50% showed remarkable organelle swelling and disruption, electron-dense granules, and cell lysis. Conclusion: One minute of exposure to ICG 0.25%, MB 0.20%, GV 0.01%, TB 0.40%, and FS 10% appeared to be safe as determined by no cytotoxic effects on rabbit corneal endothelial cells in culture.