Experimental Study On The Protective Effects Of BN52021 To The Retina After Blunt Injury In Cats

ObjectiveTo investigate the protective effects of BN52021 on the retina after blunt injury by observation of the results of electroretinogram,optic coherence tomography and histopathological changes,as well as the ultra-structure changes of anterior optic nerve.Methods1.Animal model establishing:Based on the literatures,a smooth-tiped steel products weighted 195g falls from 55cm freely to the cat's eye, to create the blunt injury model.2.Animal groups:Twenty five health cats,weighted from 2.5kg to 3.5kg,were randomizely divided into 5 groups,each group has 5 cats. A:injury group,B:solvent comparison group,C:with low concentration BN52021 group,D:with moderate concentration BN52021 group,E:with high concentration BN52021 group. Normal values were obtained from another 15 health cats.3.Examination of retinal function:At 4h,1d,3d,7d after injury,flash electroretinogram was performed and the results were statistically analyzed.4.Retinal thickness,retinal histopathological and anterior optic nerve ultra-structure observation:Retinal thickness was measured by optical coherence tomography,retinal histopathological changes and anterior optic nerve were examed by microscopy and electromicroscopy.5.Intraocular pressure measured:IOP was measured by Schi(o|¨)tz tonometer following blunt injury,and the lOP was measured atld, 3d,7d before periglomerular injection of BN52021.Results1.Twenty-five eyes were created to be blunt injury models successfully without eyeball rupture and vitreous hemorrhage.2.The Ab of Group D and E had a great recovery at day 7,group C take the second place.Lb and La of each group are delayed.Group E had a great recovery at 7d time point.Group A,B,C have a low level of Ab and Aa,Lb and La have a higher level.3.Result of OCT:Low-grade macular edema was noted in all eyes of each group at 4h.Group E showed a significant recovery in the thickness of the retina compared with others P<0.05.4.Turbulence of the retinal ganglion cell layer and retinal nerve fiber layer was observed at 4h,while group A had the most severe degree at 4h time point.At day 7,group E showed a completely recovery of the above structure.5.At 4h and day 7,the anterior optical nerve had a well-proportioned columniform appearance under light microscope.Under electro-microscopy, the optical nerve fiber's myelin sheath exhibit diastasis, and intra-cellular vacuoles were observed.Group A was more obvious than group E.6.IOP was higher measured instantly after injury than normal, P<0.05.Conclusion1.Smooth-tiped steel products weighted 195g falls from 55cm freely can create blunt eye injury model simply and feasibly.2.Compared with control group and traumatic group,BN52021 treated group had a better recovery of ERG values and histological changes. The dose dependent relations were noted.3.OCT examination demonstrated that BN52021 had a function to make the retinal edema subsided significantly,and the dose dependent effects were noted.4.Blunt injury can result in a temporarily IOP elevation in the model eyes.However,the IOP kept in normal range in the natural course after blunt ocular injury.5.BN52021 had a protective function on the retina and anterior optic nerve of blunt ocular injury model eyes in cats.