| Objective: Glaucoma is a kind of ophthalmopathy which could grow blind.And the morbidity is growing up with the increasing of elderly.To make the intraocular pressure under the target iop stabely,and try the best to keep the left visual function without deterioration. Although the new technology, new method appears continuously such as new drugs and laser therapy , glaucoma filtration surgery especially trabeculectomy still the major treatment when medical and laser therapy fail to control intraocular pressure.However,the failing rate of simple trabeculectomy is high. The principal cause of failure is fibroblast proliferation, and the appearance of scar of fitration space which influences the long-term effects.Agents that interfere with wound healing improve the success rate of glaucoma filtration surgery both in experimental animals and in patients.They make some effects in keeping the filtering pathway open, filtering bleb effective and the ocular hypotension.However,they are associated with adverse side effects and suffer certain restriction in clinical application.Tissue-type plasminogen activator(t-PA)is a new drugs in fibrinolytic that is a kind of proteinases which obtained by cloning and expression of human genes t-pa.The major enzymatic action of tPA is the conversion of plasminogen into plasmin,an active serine protease that hydrolyses fibrin,hence it makes an important role in the treatment of systemic thromboembolism disease. Recent reports also applied in ophthalmologic operation and in the treatment of fibrin, but have not seen the published report the application of combination of MMC and t-PA in glaucoma surgery in filtration.The objective of this experiment is to observe the the effect in scar reducing of trabeculectomy and the formation of safety and effectiveness by the comparison of the simple trabeculectomy,combined with single MMC or t-PA,and combination application of MMC and t-PA.And finally to find a ideal method in the glaucoma filtration surgery.Methods:1 Animals Forty New Zealand white rabbits were randomly divided into four groups:control (group A),MMC (group B),t-PA (group C)and combined MMC and t-PA (group D).Each group has ten rabbits.2 Operation We operated on every rabbit eye according to standard of trabaculactomy, and placed a piece of cotton with 0.3mg/ml MMC for 5 minutes in group B,injected into the anterior end of operation with 250μg/ml t-PA0.1ml and the conjunctival injection with 0.2ml in the 1st,3rd day after operation in group C,placed a piece of cotton with 0.2mg/ml MMC for 5 minutes and injected into the anterior end of operation with 200μg/ml t-PA0.1ml and the conjunctival injection with 0.2ml in the 1st,3rd day after operation in group D.3 Observation after operation: We used the slit lamp to observe the conjunctival wound healing, filtration blebs,filtering passage,transparency of cornea,reaction of the anterior chamber, transparency of lens after trabeculectomy.The observation were carried out on postoperative days 3,7,14 and 28 respectively.4 Intraocular pressure measurement: Intraocular pressure(IOP) measurements were performed before surgery and on postoperative days 3,7,14 and 28 respectively.We compared the difference among the four groups on different stages.5 Histopathology Two rabbits were killed on postoperative days 3,28 every group,three rabbits were killed on postoperative days 7,14 every group.We kept their filtration blebs,enucleated their eyes,fixed them,made paraffin slices. We observed the filtration passage by performing H·E staining. The collagen formation was observed by masson trichrome staining.We observed the expression of proliferative cell nuclear antigen(PCNA) in the filtration area and counted the number of positive cell nuclear under microscope after performing immunohistochemical staining.Results:1 The change of the IOP: There was no significant difference of the IOP among four groups before operation and postoperative days 3(P>0.05); The difference was significant between the group A and group B,C,D on the following stages after postoperative days 7 (P <0.05). There was difference between the group A and group B,C,however, there was no significant difference between the group B and group C (P >0.05),on the following stages after postoperative days 7 (P <0.05).2 The comparison of filtration blebs: There are all funfunctional filtration blebs in the four groups on postoperative days 3 ;Compared with the group A, the percentage of the functional filtration blebs was significantly higher in the other three experiment groups; The percentage of the functional filtration blebs of the group D was higher than that of group B and group C.3 The bulbar conjunctiva of all the four groups healed well.4 The comparison of injured corneal epithelium and conjunctival leaking wound:The percentage of injured corneal epithelium of the group B,C,D was lower than that of group A at days3,7 after surgery.All corneals healed up at 14 days after surgery.5 Anterior chamber All reaction of the anterior chamber disappeared in 3 days; All groups had no complication of corneal edema, shallow of anterior chamber, exudation, chorioretinal detachment and so on; Two eyes had hyphema from the group A and group C,but absorbed in three days.6 Lens There were no muddy in each group.7 Fundus There were no retinal detachment, macular edema and other postoperative complications.8 Histopathology observation8.1 H·E staining More inflammatory cells have been seen in early postoperative filtering area of all the four groups,and the group A was more serious. All filtration passage were opened at 3 days after surgery.The percentage of opened filtration passage of the control group was lower than the other three experiment groups in the 7,14,28 days.And it was higher in group D than group B,C.8.2 Masson trichrome staining There was no collagen in the wound area on 3 days after surgery in four groups. But at 7 days after surgery, some collagen was seen in the group A. At 14 days after surgery, there was seldom collagen in the other three groups,while the dense collagen appeared in the control group at the same time.Time came to the 28 days after surgery, collagen was still kept in a small amount of loose in experiment group D.8.3 Immunohistochemical staining:Observed at different time points after postoperative day, the number of positive cells were the most with nuclei of different shape at the 3rd day. And the number of PCNA positive cell nuclear had significant difference between the group A and the other three groups (P<0.05),and the result showed that the former one was heavier. With time, the number of positive cells gradually decreased, and form the nucleus became regularly. The expression of experiment group D was weakly than experiment group B,C in postoperative days 3and 7,and there was no significant difference between the experiment group B and C(P >0.05). There was no significant change in expression of PCNA after 14 days after surgery among the four groups.And there wasn't any obviously proliferation.Conclusions:1 Rabbit trabeculectomy with t-PA can inhibit the proliferation of Fb to reduce scar formation and maintain the functional filtering bleb.2 Rabbit trabeculectomy with lower-dose mitomycin C combined with t-PA can make more effection on anti-proliferation and less side effect than application with single MMC.3 Trabeculectomy with mitomycin C combined with t-PA treatment of glaucoma implants are safe, effective new ways to improve the success rate of surgery. |
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