The Pathohistology Changes Of The Autogenous Vein Graft After Reconstructing Lacrimal Cancanaliculus In Rabbits

ObjectiveBecause of the superficial position of the lacrimal canaliculus,lesions of lacrimal canalicular,espesilly the lower canaliculus,are often associated with eyelid trauma. Severe eyelid trauma often leads to full range lesions of lacrimal Canalicular.If the injury of the lacrimal canaliculus can not be repaired in time by surgery,it may lead to scarring and stenosis,which in turn causes tearing,and brings the uncomfortable to patient.We usually use the conjunctivodacryocystostomy or set the holdfast in the lacrimal passages to repair the lacrimal passages at present.But the physiological position of the dacryocyst is changed when have the conjunctivodacryocystostomy, and the dacryocyst lost the syphonage.So after the operation the patient still have the symptom of dacryostegma;The tube always displaced and the lumens often be obstructed by the granulation tissue when the man-made tube was put into the lacrimal passages.All of these influence the effect of this treatment.Reconstructing lacrimal cancanaliculus by the autogenous vein graft keep the physiological structure and function of the lacrimal passages.And autogenous vein graft can be taken conveniently.From 1960s,using autogenous vein graft to reconstruct lacrimal drainage system were continuously reported,but those thesises are always on clinical application,without experimental study,and could not be recognized by eye doctors.In this experiment,an animal model with reconstructing lacrimal cancanaliculus by the autogenous vein graft was made in rabbit between the conjunctival sac and lacrimal sac when the lacrimal canaliculus injuried extensively.The healing process of the autogenous vein graft was observed,in order to provide some experimental data for clinical application.Materials and Methods1 Animal and grouping39 healthy adult Japanese albino rabbits without eye diseases were divided into 3 groups randomly:normal control group,palpebral conjunctiva to lacrimal sac group and lacrimal lacus to lacrimal sac group.6 eyes of 3 rabbits were randomly assigned as the normal control group,anther 36 rabbits(72 eyes) were divided into 2 surgery group(one eye is in palpebral conjunctiva to lacrimal sac group and another is in lacrimal lacus to lacrimal sac group of each rabbit),36 eyes in each group.Then divided these rabbits into 6 groups at 6 time points and there are 12 eyes in each group.2 Methods of surgeryTake the vein of the rabbit's ear(length of 10-12mm) after the general anaesthesia,and slip it(length of 8-10mm)onto the silicon tube.Cutting the lacrimal sac from the lacrimal punctum,and make a passage from the conjunctival sac to lacrimal sac.Put the vein into this passage and suture the two sides of it.Fix the silicon tube on the conjunctival sac side on the lid-margin and put the other side into the nasolacrimal canal.Close the cut of the lacrimal sac at last.Normal control group was not operated.3 Observation items and the time pointsObserve the postoperative patent information of lacrimal drainage system,the general state of health of the eyes,the morphology of the autogenous vein and record the pathological changes of the grafted vein by immunohistochemistry stain on the 1th, 3th,5th,7th,14th and 28th post-operative day.Normal control group was observed with the same items.4 Statistical analysis Statistical analysis was performed with SPSS11.0 software.The measurement data expressed as x±s.Palpebral conjunctiva to lacrimal sac group and lacrimal lacus to lacrimal sac group were compared using Student's t-test;Palpebral conjunctiva to lacrimal sac group,lacrimal lacus to lacrimal sac group and normal control group were compared using one-way analysis of variance.Results1 Postoperative patent information of lacrimal drainage systemLacrimal lacus to lacrimal sac group on the 14th post-operative day and palpebral conjunctiva to lacrimal sac group on the 28th post-operative day,lacrimal passage have totally recovered the function of lacrimal passage,and the interval time of a positive result of fluorescein disappearance test(FDT) has no significant differences among normal control group,lacrimal lacus to lacrimal sac group and palpebral conjunctiva to lacrimal sac group(P＞0.05)2 General state of healthThe conjunctival congestion and edema appears seriously,and much secretion can be seen,the symptom of dacryostegma is obviously on the 1th post-operative day.The conjunctival congestion and edema are getting better,the secretion decrease and the symptom of dacryostegma is anesis on the 3th post-operative day.The conjunctival edema is extinct,and the secretion limited around the silicon tube,the the symptom of dacryostegma improved obviously on the 5th post-operative day.The conjunctival congestion is just appears around the silicon tube,some of the rabbit still have the symptom of dacryostegrna on the 7th post-operative day.From 14 day to 28 day after the surgery there is no typical appearance.The rabbits in palpebral conjunctiva to lacrimal sac group is similar to these in acrimal lacus to lacrimal sac group.3 Healing process of autograft vein after surgery3.1 General appearance of the autogenouse veinOn the 1th and 3th post-operative day,the vein hyperemia and edema seriously, there are much secretion in the lumen of blood vessel.On the 5th post-operative day, the hyperemia and edema are getting better,and the secretion is decrease.On the 7th post-operative day,the edema of the conjunctiva is extinct and the dividing line between the vein and the tissue around is not obvious.On the 14th post-operative day, the vein is similar to the tissue around and it is hard to tell the difference.On the 28th post-operative day,it just can recognize the vein from the suture line on the two side. And it appears no conspicuous difference in the 2 surgery groups.3.2 Result of HE stainOn the 1th and 3th post-operative day,the endothelial cells of autograft vein began to fall off,and the smooth muscle cells degenerated.On the 5th post-operative day,the fibroblast hyperplasia,the smooth muscle cell begin to crash.On the 7th post-operative day,the new endothelial cells migrated to the autograft vein,and the collagenoblast cells proliferated in propria lamina.On the 14th post-operative day,the fibroblast cells proliferated actively in propria lamina.On the 28th post-operative day, most part of the intine of the vein has been covered by the new epithelia and there were still many fibroblast in propria lamina.The result of HE stain seems similar in the 2 surgery groups.3.3 Cell proliferation of autograft vein(Result of PCNA immunohistochemistry)Most of the positive cell are under the epithelium on the 3th post-operative day, the index number of the PCNA positive cell of the epithelial cell increase obviously, and the index number of the PCNA positive cell of the epithelial cell and fibroblast reached a peak on the 7th post-operative day.After that it decreased gradually.The index number of the PCNA positive cell of the epithelial cell and fibroblast bewteen palpebral conjunctiva to lacrimal sac group and lacrimal lacus to lacrimal sac group have no significant difference at the six time points we observed(P＞0.05). The index number of the PCNA positive cell of the epithelial cell and fibroblast cell of palpebral conjunctiva to lacrimal sac group and lacrimal lacus to lacrimal sac group are significantly more than that in normal control group on the 28th post-operative day(P＜0.05).Conculsions1.Reconstructing lacrimal canaliculus by autogenous vein graft(8-10mm long),the autogenous vein reconstruct and form a new lumens.2.Reconstructing lacrimal canaliculus by autogenous vein graft(8-10mm long),on the 14th post-operative day in palpebral conjunctiva to lacrimal sac group and on the 28th post-operative day in lacrimal lacus to lacrimal sac group lacrimal passage have recovered the function.3.Reconstructing lacrimal canaliculus by autogenous vein graft(8-10mm long),the grafted vein is covered by the epithelia of palpebral conjunctiva and lacrimal sac,and it is not finished on the 28th post-operative day.The smooth muscle cells degenerated and reconstruct,and the vein graft still in the condition of proliferative.