This multicenter, randomized clinical trial compared 2 methods for applying mitomycin C (MMC) in eyes undergoing trabeculectomy.
Study design
Investigators enrolled 80 consecutive patients undergoing trabeculectomies. Patients received either conventional intraoperative application of MMC-soaked sponges (0.02%) or a preoperative injection of MMC into the subtenon space (0.01 ml of 0.01%).
Patients were evaluated at months 1, 3 and 6. The primary outcome was IOP, and secondary outcomes included endothelial cell count (ECC) and bleb morphology rated by the Indiana Bleb Appearance Grading Scale (IBAGS).
Outcomes
Complete success—IOP between 6 to 15 mm Hg without medication—was achieved in 82.5% (n=33) of patients in both groups at 6 months. There was no difference in mean postoperative IOP values or ECC between groups at all time points.
The blebs from the injection group, however, had significantly lower height and less vascularization and were more diffuse than those treated with sponges (all P<0.05). Rates of cystic blebs, bleb leaks and need for bleb needlings were no different between groups.
Limitations
In the sponge group, the length of time that MMC application soaked sponges was not standardized. The authors did, however, perform a subanalysis and found there were no significant differences between leaving sponges in place for 1 or 3 minutes. The authors did not examine the effect of different MMC concentrations.
Clinical significance
This study lends more evidence to the benefits of using a previously described MMC injection technique. The authors demonstrate that the use of MMC via a subtenon injection is at least as good, if not better, than MMC-soaked sponges in controlling IOP. Blebs in the injection group had more favorable configurations, and thus may carry less risk for complications such as hypotony and endophthalmitis. The authors also appropriately argue that the use of an injection allows for an exact amount of MMC to be used without the variability associated with sponge applications.