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Editors Selection IGR 12-4

Surgery: Ranabizumab + MMC

Comment by Rohit Varma on:

26412 Bleb morphology and vascularity after trabeculectomy with intravitreal ranibizumab: A pilot study, Kahook MY, American Journal of Ophthalmology, 2010; 150: 399-403

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Kahook (1385) performed a single surgeon pilot study to assess the effects of using intravitreal ranibizumab (0.5 mg/0.05 ml) in addition to the intraoperative use of Mitomycin C (MMC) (0.4mg/ml) on trabeculectomy success. Ten patients who underwent fornix based trabeculectomy were randomly assigned to two groups ‐ MMC alone or MMC and intravitreal ranibizumab (RAN). The patients received standard postoperative care including topical antibiotics and steroids. The primary outcome measures were bleb morphology/vascularity and intraocular pressure (IOP) differences between the two groups. Patients were assessed preoperatively and six months postoperatively. Compared to the MMC alone group, patients receiving MMC and intravitreal RAN had more diffuse and avascular blebs at six months. Bleb morphology is an important secondary measure of success particularly as it may impact potentially vision threatening complications such as infection and hypotony. The second primary endpoint was IOP. Mean intraocular pressure at baseline were similar ‐ 20 mmHg in the MMC and 17 mmHg in the MMC+RAN group (p = 0.48). Postoperatively the IOPs were also similar ‐ 9 mmHg and 11 mmHg in the MMC and MMC+RAN groups respectively (p = 0.14). The author accurately states that 'IOP values prior to surgery and at 6 months were similar between the two groups'. However, the mean drop in IOP was 11 mmHg in the MMC group and 6 mmHg in the MMC+RAN group. While these differences may not be statistically different due to the small sample size (n = 5 in each group) and the relatively short-term follow-up, these are large differences that deserve further evaluation. This is particularly important since the primary goal of glaucoma surgery is to lower IOP adequately to prevent progressive optic nerve damage and visual field loss, thereby maintaining the patients' quality of life.

Bleb morphology is an important secondary measure of success particularly as it may impact potentially vision threatening complications such as infection and hypotony

The secondary endpoints in the study were bleb-related leaks, endothelial cell counts and change in visual acuity. There were no blebrelated leaks in either group and no statistically significant differences in endothelial cell counts within or between the two groups. Visual acuity decreased in both groups (logMAR 0.10-0.11 in the MMC and 0.11-0.15 in the MMC+RAN group). While there does appear to be a greater decrease in visual acuity in the MMC+RAN group compared to the MMC-alone group, it is not clear if these differences were significant. These declines in visual acuity are attributed to greater lens opacification although no formal lens grading was performed. Finally, to carefully rule out any other causes of intravitreal ranibizumab related decline in vision, it would be important to document any changes in the optic nerve, retina and on visual field testing. In summary, the author is to be congratulated for being creative in identifying a possible role for intravitreal ranibizumab in improving the success of trabeculectomy. As the author acknowledges, while these results are promising, more work needs to be done in further evaluating what role ranibizumab may play. Areas that deserve further study include: longer term data on IOP and lens opacification, use of ranibizumab injections in the anterior chamber or in the subconjunctival space and safety data assessing the optic disc and peripheral visual fields.

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