The Effect Of Prevention Of Plasmin On Posterior Capsule Opacity

Objective: With the constant improvement of the technology of surgical microscope and the equipment, the complications of the modern extra capsular cataract extraction has been significantly reduced , after cataract (AC), also known as posterior capsular opacification (PCO),has become the most common and serious complication of surgery and seriously affected recovery of cataract patients'long-term vision after the surgery. Therefore, how to effectively prevent the formation of PCO has become an urgent problem of Ophthalmology scholars. To current, the pathogenesis of this disease has not been fully elucidated. In recent years, some studies shown that basic fibroblast growth factor (bFGF) and fibrin plays an important role on formation of the PCO. Plasmin is hot spot of ophthalmology research as the specific degradation of fibrin to induce posterior vitreous detachment, but it use in the PCO has not been reported. In this study, we imply the extra capsular cataract extraction on the New Zealand white rabbits to produce PCO animal model. Application slit lamp observation of anterior chamber inflammation and PCO's formation; application light microscopy to observe lens epithelial cells (LECs) of the posterior capsular and observe the affection of plasminogen on the cornea and retina; application proliferating cell nuclear antigen(PCNA) using semi-quantitative immunohistochemical detect proliferation of LECs on posterior capsular; application of ELISA to monitor the content of bFGF in aqueous humor after surgery to investigate the mechanism of plasminogen. The experiment is to investigate the inhibitory mechanism of plasmin on the formation of PCO and to provide the theory and experimental evidence of clinical application.Methods: Clean grade 20 New Zealand white rabbits aged 4 months, weighing 2.5-3.0kg, with no pathological changes of the eyes. The rabbits were randomly divided into two groups: control group and experimental group. Each group was 15 rabbits. All the rabbits is performed phacoemulsification under the general anesthesia. After surgery, the experimental group is injected 0.2ml 5IU/ml plasmin in the anterior chamber and the control group with no treat. We give the eye drops of tobramycin/dexamethasone 6/day for one week. From the second week, we give the eye drops 4/day for two weeks. We examined the eyes on the 1st, 3rd, 1 week, 2 week, 1 month, 2 month. On the day, we observed and noted the time, level, position of the PCO, the level of the conjunctiva congestion, corneal edema, inflammation in anterior chamber and distilled 0.2ml humor from aqueous humor to monitor the level of the bFGF's content by ELISA. Two months later, we adopt air embolism to execute the rabbits and enucleated eyeball. We fixed the eyeball in 4% Para formaldehyde solution for a week, embeds in paraffin to make tissue sections and stained in HE for light microscopy to observed the form of the LECs, cornea and retina and observed expression of LECs proliferating cell nuclear antigen (PCNA) by immunohistochemical staining. Statistics analyses were used by SPSS 13.0 software package.Result: 1.Inflammation in anterior chamber:On the first day, all the eyes of the two groups come out to be the varying degree of inflammation in anterior chamber after the surgery. On the third day, there is still 14 eyes with inflammation of the experimental group, but 19 eyes in control group. The inflammations of the two groups were statistically significant. After one week, inflammation of the experimental group return to the normal, but 6 eyes in the control group still behave inflammation. The 6 eyes were return to the normal on the second week. The time of sustained inflammation in anterior chamber: the experimental group is 6.20±1.64 days and the control group is 8.90±3.53 days. The time of sustained inflammation were statistically significant (P<0.05).2. Before and after the surgery of intraocular pressure: experimental group and control intraocular pressure showed no significant difference (P> 0.05), but at different times before and after surgery there was significant difference (P <0.05). Before surgery, intraocular pressure is 23.46±2.46 mmHg. On the 1st, 3rd day after surgery, intraocular pressure is 32.13±3.55 mmHg,26.67±2.79 mmHg. There is a significant difference. On the 1st, 2nd, 4th, 8th week, compared with preoperative intraocular pressure it is no significant difference (P >0.05).3. PCO's slit lamp photography: Posterior capsule opacity started appearing in the experimental group after 2 week and started appearing in the control group after 1 week. After 2 months, the experimental group: posterior capsule opacity appears in 9 eyes.Ⅰ-level 5 eyes andⅡ-level 4 eyes; the control group: posterior capsule opacity appear in 18 eyes,Ⅰ-level 7 eyes,Ⅱ-level 5 eyes andⅢ-level 6 eyes. The incidence of the PCO: the experimental group was 45% and the control group was 90%, statistically significant difference (P <0.01). PCO occurred in time: the experimental group is 2 month; control group is 1 month, statistically significant difference (P <0.01); turbidity score of the PCO: the experimental group was 0.65±0.81, control group: 1.75±1.02, statistically significant difference (P <0.01).4. Posterior capsular tissue pathology: HE staining for posterior capsule: The experimental group: Lens epithelial cell was rare and arrange in a single membrane. Only few fibroblasts can be seen in the posterior capsule; the control group: Lens epithelial cell arrange in multi-layer membranes. Lots fibroblasts can be seen in the posterior capsule. HE staining for corneal: two group of cornel's structural was integrity. Corneal endothelial cell detach from the internal elastic layer in somewhere. HE staining for retina: two group of retina's structural was integrity. The ganglion cells were in the same size. Its outline was ruler. Its boundaries were clear.②immunohistochemistry: Nuclear stained brown or yellow is positive results. In the experimental group, single cell staining can be seen in the posterior capsule. In the control group, multi-cell staining can be seen in the posterior capsule. The average OD value of experimental group was 31.7± 3.8 and the control group was 61.3±4.0. The two groups were statistically significant (P<0.05).5.ELISA for the determination of the concentration of bFGF in aqueous humor of anterior chamber:On the 1st , 3rd , 7th day, 2nd ,4th week after surgery, the concentration of bFGF of the experimental group were respectively 0.78±0.19ng,0.38±0.12ng/ml,0.68±0.21ng/ml, 0.81±0.31ng/ml,0.93±0.21ng/ml. The control group was respectively 15.88±1.38ng/ml,14.34±1.21ng/ml,9.13±1.25ng/ml,4.87±0.76ng/ml,2.75±1.01ng/ml. The concentration of bFGF of the experimental group was significantly lower than the control group (P <0.05). On the 2nd months after surgery, the experimental group was 0.99±0.23ng/ml and control group was 1.11±0.32ng/ml. There was no statistically significant (P > 0.05).Conclusion:1. Postoperative anterior chamber injection of plasmin reduces inflammation of the anterior chamber and promotes the recovery of inflammation,2. Plasmin can effectively reduce the incidence of posterior capsule opacity and slow down the pace of development3. Plasmin can reduce the content of bFGF in aqueous humor of anterior chamber...