Figure 2. H₂O₂ dose-dependently decreased cell viability of retinal pigment epithelial cells as tested by microculture tetrazoline test. Retinal pigment epithelial (RPE) cells were plated in 96-well plates and treated with various concentrations of H₂O₂ for 24 h. Cell viability was evaluated by the microculture tetrazoline test (MTT) test and expressed as percentage of that in cells without H₂O₂ (mean±standard deviation [SD] in triplicate tests). A: H₂O₂ showed dose-dependent cytotoxic effects on ARPE-19 cells (cells from an immortal RPE cell line from a 19-year-old donor) at concentrations from 0.25 mM to 1.00 mM (p<0.05, compared to cells cultured without H₂O₂. B: Studies of primary cultures of human RPE cells isolated from donor eye showed similar results. *p<0.05, compared with the controls (cells cultured with H₂O₂ alone).