Morphological and functional changes of optic nerve and retina following optic nerve crush in rat

Objective:To understand the featares of morphological and functional changes of optic nerve and retina after optic nerve crush.Methods:The changes of optic nerve and retina were observed using the light microscope and electron microscope,and the visual evoked potential response to flash (F VEP)was recorded in normal and optic nerve crush rats.Results:Retinal ganglion cells (RGCs) were reduced significantly due to partial lesion of optic nerve crush.An initial loss was accelerated by 2 weeks after nerve crush,thereafter declines was protracted in RGCs densities.Under electron microscopy chromatin aggregation of RGCs became conspicuous.Cell bodies were prominently furrowed.Condensed nuclei presented in the retina.Cytoplasmic atrophy was profound,and nucleus membrane was in its integrity.Other injured ganglion cells membranes might be dissolved and showed dropsy and disintegration of organelle.Under electron microscopy and light microscopy,the optic nerve fiber collapsed and their axons showed vacuolation after optic nerve crush.Glial cell showed hyperplasia.The latency extended and the amplitude was depressed 1 hour after crush.No response was observed in animals 4 weeks later.Conclusion:It shows that the excessive loss of neurons due to secondary degeneration following optic nerve crush is the most important factor for visual impairment.Therefore,it is highly crucial to protect neurons from secondary damage for improving visual function.