[Abstract] Objective To observe the clinical efficacy of combined trabeculectomy with intraoperative application of mitomycin and postoperative application of interferon in the treatment of neovascular glaucoma. Methods In 17 cases (17 eyes) of neovascular glaucoma, mitomycin was applied intraoperatively at a concentration of 0.4 mg/ml for 2 minutes, and interferon 5×105 IU was injected subconjunctivally in the parafiltrate area at the time of surgery, and at the 3rd, 7th, 10th and 14th postoperative days, respectively. We observed the postoperative effect of interferon in preventing the formation of scarred follicles, the effect of IOP lowering and the success rate of surgery. The IOP of 17 patients with neovascular glaucoma was normalized 6 months after surgery, from 36.42±5.64 mmHg before surgery to 15.73±2.99 mmHg (t=11.465, p<0.01), and the corneal transparency was restored, and the neovascularization of the iris surface was completely eliminated or only minimal. The success rate of surgery at 12 months after surgery was 94.1%. Conclusion Trabeculectomy combined with intraoperative mitomycin and postoperative interferon for neovascular glaucoma can effectively control IOP, relieve pain, promote neovascularization, and preserve residual visual function and ocular shape. Li Xiaodong, Ophthalmology Department, Baicheng Central Hospital
【Key words】 mitomycin; interferon; glaucoma
Neovascular glaucoma is recognized as a refractory glaucoma and is one of the challenges in the clinical treatment of ophthalmology. Neovascular glaucoma is mostly secondary to retinal ischemic diseases such as retinal vein obstruction, diabetic retinopathy, or fundus diseases such as inflammation and retinal choroidal hemangioma. Due to the formation of neovascularization and connective tissue membrane on the iris surface and anterior chamber angle, the iris and trabecular meshwork in the peripheral part are closely adhered, destroying the normal structure of the atrial angle, resulting in poor drainage or anterior displacement of the crystalline iris diaphragm and closure of the atrial angle, causing an increase in IOP, which is difficult to control with medications, and the success rate of conventional filtration surgery is only 11% to 52%. Trabeculectomy combined with interferon and trabeculectomy combined with mitomycin have been reported [1 .2], but trabeculectomy combined with intraoperative application of mitomycin and postoperative application of interferon α-2b for neovascular glaucoma has not been reported in the literature. Therefore, in our department, we have been using trabeculectomy combined with intraoperative mitomycin and postoperative interferon for neovascular glaucoma since May 2003, and the results were satisfactory at 6-15 months of postoperative follow-up.
Materials and methods
1. General data: The authors treated 17 cases (17 eyes) of neovascular glaucoma admitted from May 2003 to October 2006 with trabeculectomy combined with intraoperative application of mitomycin and postoperative application of interferon. Among them, 7 cases were male and 10 cases were female, aged 35-70 years, with a mean of 52.3 years. The mean preoperative IOP was 36.42±5.64 mmHg.
2. Methods: (1) The surgical method was the same as conventional trabeculectomy. (2) Application of mitomycin: mitomycin was used intraoperatively for a single time, and a cotton pad was blotted in a solution containing 0.4 mg/ml mitomycin, and after making a scleral flap, the exposed scleral surface and scleral flap bed were contacted with a wet cotton pad cut into 3 mm×4 mm size for 2 min, and the trabeculectomy was performed after the trabeculae were flushed with 250 ml of balanced solution. (3) Application of interferon α-2b: Diluted interferon 5×105 IU was injected subconjunctivally at the time of surgery, 1d, 3d, 7d and 14d postoperatively near the filter bulb of the operated eye. the medication was changed daily after surgery and slit lamp examination was performed. The postoperative period of 6 weeks focused on the observation of conjunctival incision, filtration follicle, cornea, anterior chamber and intraocular pressure changes, and the long-term follow-up focused on visual acuity, intraocular pressure and filtration follicle morphology. (4) Judgment of efficacy: postoperative IOP control with or without IOP-lowering drugs at 6~21 mmHg was considered successful; postoperative IOP >21 mmHg was considered a failure if IOP-lowering drugs could not be applied to lower IOP. The postoperative outpatient follow-up was 6 to 15 months. Statistical treatment was performed by t-test.
Results
The mean IOP decreased from 36.42±5.64 mmHg before surgery to 15.73±2.99 mmHg (t=11.465,p<0.01), and the corneas regained transparency, and the neovascularization of the iris surface completely disappeared or only rarely remained. The follicles were staged (according to Kronfeld staging), i.e., type I was microcystic, type II was diffusely flattened, type III was absent, type I and II were functional follicles, and type III was nonfunctional follicles. At the one-year postoperative follow-up, functional follicles were formed in 16 of 17 eyes and nonfunctional follicles were formed in one eye.
DISCUSSION
The treatment of neovascular glaucoma is tricky [3]. Conventional methods include (1) topical ocular medications and oral and intravenous administration: however, it is difficult to control the disease and there are serious hazards such as interference with the cardiovascular system, impact on renal function and electrolyte imbalance, which prevent long-term use. (2) Destructive ciliary condensation or transscleral ciliary photocoagulation: due to its indeterminate amount, the ciliary body is highly damaged, and reactive high intraocular pressure, severe uveitis, and eventually uncontrolled intraocular pressure or ocular atrophy often occur after surgery. (3) Conventional filtration anti-glaucoma surgery: because of the atrial angle closure and a large number of neovascularization, intraoperative bleeding is extremely easy, and postoperative blockage of the filtration port by neovascularized fibrous membrane will occur, with uncontrolled IOP and eventual removal of the eye. (4) Early extensive retinal photocoagulation: the efficacy is certain and the neovascularization can be degraded, but most of them cannot solve the IOP problem. It is difficult to establish effective filtration channels after neovascular glaucoma surgery, so the success rate is only 11% to 52%. In this paper, we observed the effect of trabeculectomy combined with intraoperative application of mitomycin and postoperative application of interferon in the treatment of neovascular glaucoma, and achieved satisfactory results. The reasons for the success of this approach are as follows: (1) mitomycin is a component of a mixture of ethylenimine antibiotics produced in Streptomyces capitis. Its action is to inhibit DNA replication in proliferating cells. A single dose of mitomycin during glaucoma filtration surgery can effectively inhibit fibroblast proliferation, reduce scar proliferation, prevent follicular adhesions, and improve the success rate of surgery. In order to prevent the occurrence of mitomycin toxic effects, we use the minimum effective dose and the optimal method of administration. (2) The use of interferon in glaucoma filtration surgery is based on the principle that it can inhibit fibroblast proliferation and chemotaxis, and at the same time inhibit collagen production. The possible mechanisms by which interferon α-2b inhibits scarring of the filtration tract are as follows: a. Inhibition of fibroblast division and proliferation, resulting in a decrease in the number of major cells synthesizing collagen; b. Specific inhibition of fibroblast and type I collagen mR-NA expression at the genetic level; c. Interferon α-2b inhibits fibroblast production of glucosaminoglycan and increases collagenase activity, resulting in increased collagen breakdown [4 ]; d. Local blood supply is reduced and neovascular growth is inhibited. Interferon α-2b has a large molecular weight and therefore passes through tissues slowly, and it inhibits collagen synthesis and secretion mainly and inhibits cell proliferation secondarily, therefore, it has a moderate effect with few toxic side effects and causes few complications. (3) It is difficult to establish an effective filtration tract in neovascular glaucoma by filtration surgery. The use of trabeculectomy combined with mitral resection and interference for neovascular glaucoma can keep the filtration tract open and induce the regression of neovascularization, which can better control the IOP and preserve the useful visual function.
References
1 Fang LB, Yan YN. Trabeculectomy combined with amniotic membrane implantation and interferon-2b for refractory glaucoma. Chinese Journal of Practical Ophthalmology, 2005, 23(11): 1193-1194
2 Xia Xiaobo (review). The use of mitomycin in glaucoma filtration surgery. Foreign Medical Ophthalmology Branch, 1995, 19: 21-24
3 Dai WJ, Lu Y, Xu L. Analysis of the efficacy of surgical treatment of neovascular glaucoma. Chinese Journal of Practical Ophthalmology, 2001, 19: 533-535
4 Chen HH, Yang L. Study of pseudo-drugs for eliminating scarring. Journal of Modern Integrative Medicine, 2003, 12(11):1121-1122