The aim of this study was to determine whether α-lipoic acid (LA) is effective in blunting the detrimental effect of light to transformed retinal ganglion cells (RGC-5 cells) in culture. In this study, RGC-5 cells were exposed to light (400–760 nm; 1000 lx) for 48 h with or without LA. For cell assessment, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 4-[3-(-iodophenyl)-2-(4-nitrophenyl)-2 H -5-tetzolio]-1,3-benzene disulfonate (WST-1) reduction assays were used to assess cell and mitochondrial viability respectively. Furthermore, cells were stained for reactive oxygen species (ROS), Apoptosis DNA breakdown and Apoptosis membrane alteration. Antioxidant-capacity, glutathione (GSH) and gluthathione- S -transferase (GST) were determined as well. Light reduced cell viability, affected mitochondrial function, increased the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive cells and enhanced labelling for ROS. These effects were all attenuated by the presence of LA. LA also stimulated GSH and GST. These findings support the view that light can affect mitochondria which could lead to retinal ganglion cell apoptosis and LA can blunt by decreasing ROS generation and stimulating GSH and GST.