To compare the efficacy and safety of subtenon injection of mitomycin C (MMC) with that of conventional application of MMC soaked sponges in trabeculectomy.

In this multicenter randomized clinical trial, 80 consecutive open angle glaucoma cases were randomized into 2 groups; group 1 received a subtenon injection of 0.1 ml of 0.01% MMC, while group 2 received 0.02% MMC soaked sponges for 1-3 minutes. Primary outcome measure was intraocular pressure (IOP), and secondary outcome measures were endothelial cell count (ECC) changes and bleb morphology according to the Indiana bleb appearance grading scale (IBAGS). Outcome measures were compared at 1, 3 and 6 months postoperatively. Complete and qualified success was defined as IOP within 6-15 mmHg without and with medications at month 6, respectively.

Mean preoperative IOP was 21.8 ± 5.1 in group 1, which reduced to 10.3 ± 3.7 mmHg at final visit (P<0.001). Corresponding values for group 2 were 21.8 ± 5 and 10.8 ± 3.5 mmHg respectively (P<0.001). Complete success was 82.5% in both groups, and qualified success was 0 and 2.5% in groups 1 and 2, respectively. (P= 0.316) The blebs tended to be more diffuse, less vascularized and shallower in group 1, at month 6 (P= 0.45, <0.001, and <0.007 respectively). Endothelial cell counts did not change significantly at final visit (P=0.813).

Subtenon injection of MMC is a safe and effective and alternative to the conventional soaked sponge method and produces more favorable bleb morphology after trabeculectomy.