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Editors Selection IGR 13-1

Surgical Therapy: Bevacizumab vs MMC with Ahmed implant

Comment by Brian Francis on:

46347 Adjunctive use of bevacizumab versus mitomycin C with ahmed valve implantation in treatment of pediatric glaucoma, Mahdy RA, Journal of Glaucoma, 2011; 20: 458-463

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The treatment of pediatric congenital glaucoma is largely a surgical one, with the traditional goniotomy and trabeculotomy as first line, and trabeculectomy and more recently aqueous tube shunts following. Adjunctive use of medications to prevent capsular fibrosis has the potential to increase the success rates of aqueous tube shunt surgery by preventing tube encapsulation.

Adjunctive use of medications to prevent capsular fibrosis has the potential to increase the success rates of aqueous tube shunt surgery by preventing tube encapsulation

In this study, Mahdy (1592) explores the use of bevacizumab, an anti-vascular endothelial growth factor antibody, compared to the antifibrotic agent mitomycin C when applied at the time of Ahmed valve implantation in pediatric glaucomas. The study design was prospective, with randomization to three groups: S3 Ahmed valve alone, or with subtenons injection of bevacizumab (1.25 mg in 0.05 ml) at the end of surgery, or with introperative MMC application (0.4 mg/ml for 3 minutes). Sixty eyes of 48 patients were included, with 20 in each group. The inclusion criteria were a diagnosis of recurrent congenital glaucoma, less than five years of age, and prior failed trabeculectomy or goniotomy surgery. Exclusion criteria were aphakia, anterior segment dysgenesis, 'disorganized' eye, or no light perception. Complete success was defined as IOP between 10 and 21 mmHg without glaucoma medications or additional glaucoma surgery, and no visually devastating complications. Qualified success included the use of medications. The results showed an increased success rate for the bevacizumab and MMC groups compared to Ahmed alone (failure rate 20%, 20% and 40%), as well as lower IOP at 12 months (15 ± 2, 14.5 ± 1.5, and 17 ± 3.1). The complication rates were similar among the three groups but did include a low rate of devastating complications such as endophthalmitis and loss of light perception. The strength of this study lies in the prospective, randomized, controlled design. The author was able to compare two experimental adjunctive treatments with Ahmed valve surgery alone. The inclusion and exclusion criteria are clearly stated, as well as the success definition. Care was taken to collect appropriate data, including complications. There are some limitations and questions that should be addressed. The first is the study population. The trial was conducted in Egypt, but we do not know the ethnicity of the patients, although it can be assumed that they are Egyptian. Although 20 eyes are included in each group, there are patients with more than one eye included. It is unclear whether each eye was randomized as a separate unit or both eyes were treated in the same manner. This does leave potential for confounding, especially with a relatively small number in each group. The conclusion section and the abstract state that bevacizumab 'seems to be much safer with no visually devastating complications' compared to MMC, but perhaps also to the control group. The assumption is that the author is referring to infection and loss of light perception vision, which occurred in two (10%) patients in the MMC group, but none in the other groups. In conclusion, this prospective, randomized trial examined the effects of Ahmed valve surgery with or without adjunctive bevacizumab or MMC. The results support their use with a greater success rate in both experimental arms after one year of follow up. The results were similar between bevacizumab and MMC, and they conclude that use of bevacizumab would be preferred due to the lower risk of complications.

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