Background Neovascular diseases such as retinopathy of prematurity often leads to irreversible vision loss.The study on oxidative damage mechanism is becoming more and more important.Whether brain derived neurotrophic factor (BNDF) has protection to retinal ganglion cells(RGCs) has few research reports.Objective The study was to investigate the expression changes of BDNFin mouse retinas of oxygen-induced retinopathy (OIR).Methods Thirty SPF C57BL/6J immature rats were divided into OIR group and normal control group and to fifteen rats for each group.OIR models were established by raising 7-day-old (P7) mice together with maternal mouse in (75±3) ％ oxygen environment for 5 days and then returned to the normal air environment,and the mice of the normal control group were raised in the normal air environment.The P17 mice were sacrificed for retinal histopathological examination by hematoxylin and eosin staining, and the number of vascular endothelial cell nucleus extending the inner limiting membrane was counted.Whole retinal mounts were prepared after fluorescein isothiacyanate-dextran (FITC-dextran) (9 ml/kg) was retrosorbitally injected,and the distribution of retinal vessels was observed in P17 mice.The relative expression levels of BNDF in retinas were detected in P13, P15, P17 mice, and the results were compared between the normal control group and the OIR group.Results Histopathological examination showed that retinal inner limiting membrane was smooth in the normal control group, but a lots of vascular endothelial cell nucleus extending the inner limiting membrane were seen under the optical microscope in the OIR group.The number of the vascular endothelial cell nucleus extending the inner limiting membrane was 1.70±0.68 in the normal group and 45.3±3.13 in the OIR group, showing significant difference between them (t =86.5, P =0.00).Whole retinal mount revealed that normal retinal vessels and network-like capillaries were exhibited in the mice in the normal group, while tortuous vessels,capillary loss and non-perfusion areas were revealed in the OIR group on the whole retina mounts.The relative expressing levels of BDNF in retinas were 263.992±9.451 and 218.432±9.710 in P15 and P17 mice in the OIR group,which were significantly higher than 230.324±7.779 and 115.846±7.305 in the normal control group (t=14.2,42.3 ,P＜0.05).Conclusions OIR can be inhibited by increasing the expression of BNDF.