Objective To observe the neuroprotective effect of alpha;-lipoic acid (ALA) on cultured retinal ganglion cells (RGC-5) under elevated pressure in vitro. Methods Cultured RGC-5cells were divided randomly into 4 groups, including normal control group (group A), negative control group (group B), elevated pressure group (group C) and elevated pressure + ALA group (group D). The cells of group A and C were not intervened with ALA. The cells of group B were treated with 200 mu;mol/L ALA. The cells of group D were treated with different concentrations of ALA (50, 100, 200 mu;mol/L) for one hour. Then cells of group C and D were exerted to 50 mm Hg (1 mm Hg=0.133 kPa) for 24 hours, while the cells of group A and B were exerted to normal pressures for 24 hours. The cell viability was measured using the methyl thiazolyl tetrazolium (MTT) assay and apoptosis was evaluated using 4prime;,6-diamidino-2-phenylindole (DAPI) staining. Expression of MnSOD was determined by realtime polymerase chain reaction (RT-PCR) and Western blot, respectively. Results The cell viability of group B was (65.6plusmn;3.4)%, which lower than that in group D of three concentrations of ALA［(75.1plusmn;3.3)%, (81.8plusmn;2.9)%,(87.9plusmn;3.1)%］, the differences were significantly (t=5.108, 10.007, 12.513;P＜0.05). DAPI staining revealed that characteristic apoptotic changes, such as chromatin condensation,convoluted nuclei with cavitations, fragmentation of the nucleus, and apoptotic bodies appeared in RGC-5cells after 24 ours pressure. There was almost no evidence of apoptosis in group D. RT-PCR and Western blot analysis revealed that the expression of MnSOD mRNA and protein were weakly expressed in group C compared with control A (t=22.045，26.979;P＜0.01). Compared group C with group D, the level of MnSOD mRNA and protein in group D increased significantly (t=9.171, 12.267, 23.567, 7.723, 12.009, 28.198;P＜0.05).In addition, the presence of ALA was found to inhibit hydrostatic pressure induced damage of RGC-5cells in a dose-dependent manner (F=134.273,194.597;P＜0.01). Conclusion ALA can effectively improve the expression of MnSOD in RGC-5cells under the condition of elevated pressure, enhance the ability of RGC-5cells against oxidative damage.