RESUMEN
Objective:To investigate the survival rate change of retinal ganglion cells（RGCs）in a mouse of optic nerve crush（ONC）.Methods:Ninety-seven male C57BL/6J mice（6 to 8 weeks）were selected and divided into normal group（ n=5）, sham-operation group（ n=5）and ONC group（ n=5）according to the random number table. In normal group, both eyes of the mice did not receive any intervention. In sham-operation group, the right eye of the mice received sham operation, while the left eye reveived no intervention. In ONC group, the left eye received ONC, and the right eye received sham operation. In normal group, the density of RGCs in both eyes was quantified and compared. In sham-operatioin group, the density of RGCs in the sham operation eye was calculated and then compared to the average density of RGCs in normal group. In ONC group, the survival rate of RGCs was set as the ratio between the left eye（ONC eye）and the right eye（sham-operation eye）. The survival rate of RGCs in ONC group was compared after crush injury for 5, 10, 20, 30 seconds）（the sacrifice time was set at day 7）, and was compared after sampling on days 3, 4, 5, 7, 14, 30, 60, 90, 180（the duration of crush injury was set as 20 seconds）. Results:In normal group, the density of RGCs in the right eye was（5, 167.3±55.6）cell/mm 2, with no statistical difference from that in the left eye［（5, 199.6±44.8）cell/mm 2］（ P>0.05）. The density of RGCs in normal group and sham-operation group was（5, 183.5±33.4）cell/mm 2 and（5, 151.5±87.6）cell/mm 2, showing no statistical difference（ P>0.05）. The survival rate of RGCs in ONC group after crush injury for 5, 10, 20, 30 seconds was（37.6±1.1）%,（34.0±0.9）%,（33.6±1.6）% and（30.3±0.6）%（ P<0.01）. In comparison, there was statistical difference in the survival rate of RGCs between crush injury for 5 seconds and for 30 seconds（ P<0.01）, but not among other duration of crush injury（ P>0.05）. The survival rate of RGCs in ONC group after sampling on days 3, 4, 5, 7, 14, 30, 60, 90, 180 was（85.4±2.0）%,（67.6±3.1）%,（43.0±1.0）%,（33.6±1.6）%,（22.7±2.0）%,（12.8±0.6）%,（10.4±0.8）%,（8.6±0.5）% and（6.7±0.2）%（ P<0.01）, showing the most obvious drop from day 3 to day 5. Additionally, the curve became flattened after 30 days. Conclusions:In a mouse model of ONC, varying durations of crushing will lead to different damage to RGCs in a progressive mode, indicating that following the primary injury（ONC）, the RGCs suffer secondary injury as well. Therefore, effectively controlling the secondary injury may be the key point of treating optic nerve injuries.