ROS generation (A) and survival (B) rates in glial cell cultures exposed to a mixture of ROS-generating compounds for 24 or 48 hours. ROS generation and cell survival, which were assessed with dihydroethidium and calcein assays, respectively, are expressed as percentages of controls. Despite ROS generation, the survival rate of glial cells after ROS-generating treatment was greater than 70% of untreated controls. All experiments were performed in triplicate and were repeated three times for each experimental condition. Data are presented as mean ± SD. ONH, optic nerve head.