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Objective To establish a rat model of optic nerve ON contusion after clamp injury， and investigate the application of manganese-enhanced magnetic resonance imaging （MEMRI） in detection of the location and extent of damage． Method 26 healthy female SD rats were randomly divided into two groups （MEMRI group and electron microscopy group）， then the MEMRI group was observed on 1 d，2 d，5 d，90 d after injury， electron microscopy group was observed at 1 d and 2 d after injury． The MEMRI group was focused on dynamic observation of ON tractography and axoplasmic transport changes on 1 d，2 d，5 d，90 d after injury， electron microscope group was focused on ultrastructural changes on 1 d and 2 d after injury． Results MEMRI findings： on T1WI all control group eyes exhibited hyper-intensity in ON， the superior colliculus and lateral geniculate body． Injury group eyes exhibited hyper-intensity in ON proximal to eye and decreased intensity in the distal end on 1 d； hyperintensity in ON proximal to eye and no signal in the distal end on 2 d； no signal in ON， the superior colliculus and lateral geniculate body on 5 d and 90 d． Electron microscope findings： dissolving axons, loosed myelin sheaths which separated from axolemma and swelled mitochondria were observed on 1 d； Further dissolved axons， dissolving microfilament and microtubule， abundance of bulb-like degeneration， swelled mitochondria with bulb-like degeneration inside were observed on 2 d． Conclusion The transport function of neuronal calcium channel can be significantly damaged after ON injury and irreversibly deteriorate with time． MEMRI may be used to evaluate the transport function of damaged neuronal calcium channel in ON and detect the location and extent of damage. [ABSTRACT FROM AUTHOR]