【摘要】目的：在兔眼行硅凝胶膜植入后，通过观察眼内压、滤过泡、病理组织检查结果评价硅凝胶膜植入的安全性和有效性。
方法：共40只兔随机分为4组，每组10只。每只兔一眼行巩膜瓣下小梁咬切术，术中植入硅凝胶膜，对侧眼单纯行巩膜瓣下小梁咬切术作为对照。术后观察眼内压、滤过泡的变化，并且每只眼行组织病理学检查。
结果：植入眼较对照眼低眼压和滤过泡维持时间长，光镜显示植入眼滤过道、咬切口区保持通畅。成纤维细胞增殖的活性与规律，在植入眼和对照眼是相似的。硅凝胶膜不会刺激成纤维细胞增殖的过度表达。
结论：硅凝胶膜植入术作为一种新型引流术具有安全、有效、操作简单的优点。
【关键词】 硅凝胶膜；引流术；眼内压
AbstractAIM:To investigate the efficacy and security of the silicone membrane implant through observing intraocular pressure, filtering blebs and histopathologic results.METHODS:Forty rabbits were randomly divided into 4 groups. Each group consisted of 10 rabbits. Trabeculectomy and silicone membrane implantation were performed in one eye of each rabbit, while the other eye was only performed trabeculectomy as control. The change of intraocular pressure, filtering blebs were observed postoperatively. And each eye had undergone histopathologic examination.RESULTS:The duration of low intraocular pressure and existence of filtering blebs in implanted eyes was longer than that in controlled eyes. Light microscopy revealed that patent drainage tract and biting site could be seen in silicone membrane implanted eye. The activity and regularity of fibroblast proliferation in implanted eyes and controlled eyes were similar. Excessive expression of fibroblast proliferation was not induced by siliconemembrane.
CONCLUSION:Characterized by safety, effectiveness and simplicity, silicone membrane implantation can act as a new drainage surgery.
KEYWORDS:silicone membrane；drainage surgery；intraocular pressure
INTRODUCTION
For glaucoma, especially refractory glaucoma, conventional filtering surgery often fails to produce satisfied result[1,2]. After drainage surgery, rabbit eyes showed intense reactions similar to those in human refractory glaucoma[3]. In order to improve the success rate of filtering surgery in refractory glaucoma, we performed silicone membrane implantation beneath scleral flap in rabbits. Intraocular pressure (IOP), filtering blebs and morphological changes were observed so as to evaluate the practicability and security of such procedure and to provide experimental evidence for its clinical use.
MATERIALS AND METHODS
Animals and Groups A total of 40 healthy white rabbits (average weight 2.02.5kg) were randomly divided into 4 groups, 10 rabbits in each group.
Methods
Preparation of silicone membrane Silicon membrane (0.02mm in thickness) was cut into rectangular pieces, 6mm×4mm
Construction of animal models All rabbits were anesthetized through intramuscular injection of ketamine 50mg/kg and chloropromazine 25mg/kg. In the experimental eye of each rabbit, trabeculectomy was performed in a standard fashion in the supratemporal quadrant with fornixbased conjunctival flaps, limbalbased rectangular scleral flaps, approximately 4mm×4mm.Then a drainage tract, 2mm×1.5mm, was made with sclerotomy punch, and the drainage tract was covered with silicone membrane, which was fixed on the sclera. At last, the scleraland conjunctival flap were sewed respectively. As control, the fellow eye of each rabbit was subject only to trabeculectomy, without silicone membrane implantation.
Postoperative IOP and filtering blebs Doyle defined that success in IOP control after operation is a reduction of 2mmHg on the preoperative basis[4]. According to Khaw, quantity of blebs is classified into 4 ranks (03)[5]. 0:complete adherence and no filtration; 1:01 oclock range of blebs; 2:12 oclock range; 3:> 2 oclock range.
In the first two weeks after the operation, IOP was determined twice a week and in the 3rd and 4th week after the operation, IOP was determined once a week. BeforeIOP determination, blebs were observed with slitlamp microscope.
Histochemical observation On the 3rd, 7th, 15th and 30th day after the operation, ten rabbits were randomly picked up and killed. Their eyeballs were excised. Slices were prepared by routine pathological sectioning, followed by HE staining or AgNoRs staining. Subsequently HE stained slices were observed under 10×microscope and AgNoRs stained slices under 100×microscope. Table 1 IOP of the implant group and control group at different timepoints(略)Table 1 shows IOP of the implant group and control group at different timepoints.(略)
IOP comparison between implant group and control group IOP comparison between two groups before the operation did not show significant difference, neither did it on the third day after operation. But on the 7th, 15th , 21th and 30th day after the operation, IOP comparison between two groups revealed significant difference (P<0.05).
IOP comparison at different timepoints In the implant group, the preoperative IOP was significantly different from IOPs on the 3rd, 7th, 15th , 21th and 28thday after the operation (P<0.01); the IOP on the 3rd day after the operation was significantly different from that on the 7th, 15th , 21th and 28th day (P<0.01); however, no significant difference was found between IOPs measured on the 7th, 15th , 21th and 28th day. In the control group, compared with preoperative IOP, IOP on the 3rd day after the operation showed significant decrease (P<0.01) while
IOPs on the other days after the operation showed no significant change compared with preoperative IOP.
Blebs Ranking After operation, bleb rank was found to be higher than that before the operation on all the observations except on the 3rd day (P<0.05), as shown in Figure 1.
HE Staining Fibroblast was the major cell observed. On the 3rd day after the operation, in both groups fibroblasts began to appear in small number in the drainage region, which had oval nuclei and some of which had protein aggregates linked by fibrous tissue. On the 7th day, more fibroblasts were observed in the implant group, which arranged in three or four layers on both sides of the silicone membrane and formed a sac. Between the sac and the silicone membrane, there was a slender void. Out of the sac, vascular endothelial cells, leukocytes and fibroblasts can be seen. In the control group, vascular endothelial cells, leukocytes, lymphocytes and fibroblasts could be found in abundance in the drainage tract and subscleral flap. On the 15th day after the operation, in the implant group silicone membrane was surrounded by fibrous tissue arranged in multilayers, which was more compact in the inner layers than in the outer layers. There was slight inflammation and the drainage tract was mostly open. However, in the control group the drainage tract was blocked by fibrous connective tissue. On the 30th day, fibroblasts were almost completely replaced by fibrocytes and many collagen fibers were produced. The blocking rates of the drainage tract were respectively 20% and 100% in the implant and the control group.
Fibroblast Proliferation Active fibroblasts were oval and in the nuclei, there were 16 AgNoRs particles, round or square, darkstained. As time went by, fibroblasts became fusiform. There were fewer and fewer AgNoRs particles and fibroblasts became fibrocytes. However, there was no significant change in the number of AgNoRs in either group. In both groups, there were more AgNoRs particles on the 7th day than on the 3rd, 15th or 30th day (P<0.01) (Table 2).
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