Excessive retinal ganglion cell loss after optic nerve crushed with forceps in rats

Objective To evaluate the injury degree of retinal ganglion cells(RGCs)after optic nerve crushed with forceps.Methods A total of 38 male Wistar rats were divided into forceps groups,which was subdivided into group A to group E,with crushing time of 12 seconds,9 seconds,6 seconds,3 seconds and 1 second,the group F was the forceps group at reverse direction,5 rats in each group.The optic nerve at temple side of rat eyeball was exposed.Optic nerves at 2 mm behind the eyeball were crushed with 90 g micro forceps and then with the 40 g forceps at reverse direction.Left eye of each rat was taken operation,and right eye was treated as normal control.Left eyes of rats in shame operation group were taken treatment to expose optic nerve behind the eyeball,but not with crush.Amount and survival rate of RGCs were calculated with fluorogold regressive labeling RGCs and retinal stretched preparation.Results Cell densities of left and right eyes of rats in shame operation group were(2 679±67)mm-2 and(2 689±53)mm-2,there was no significant difference(P=0.896),and were(220±167)mm-2,(265±232)mm-2,(298±239)mm-2,(478±682)mm-2,(769±615)mm-2 and(974±476)mm-2 in forceps groups,which were obviously decreased.There was negative correlation between impulse of forceps(force of forceps multiply time)and survival rate of RGCs.Conclusions Crush with forceps can make definite and quantitative optic injury,but the injury is serious and stability is poor.There is still a marked gap between our experiment and the actual pathogenesis of traumatic optic neuropathy.