Intra‐operative Mitomycin C for glaucoma surgery
Abstract
Background
Trabeculectomy is performed as a treatment for glaucoma to lower the intra‐ocular pressure. Mitomycin C is an antimetabolite used during the initial stages of a trabeculectomy to prevent excessive post‐operative scarring and thus reduce the risk of failure.
Objectives
The objective of this review is to assess the effects of intra‐operative Mitomycin C in trabeculectomy.
Search methods
We searched the Cochrane Eyes and Vision Group trials register, The Cochrane Controlled Trials Register ‐ CENTRAL, MEDLINE, EMBASE and the reference lists of relevant articles. We used the Science Citation Index to search for articles that cited the included studies. We contacted investigators and experts for details of additional relevant trials.
Selection criteria
We included randomised trials of intra‐operative Mitomycin C compared to placebo in trabeculectomy.
Data collection and analysis
Two reviewers independently assessed trial quality and extracted data. We contacted trial investigators for missing information. Data were summarised using relative risk, odds ratio and weighted mean difference.
Main results
This review includes 11 trials involving a total of 698 participants. The trials included three types of participants (high risk of failure, trabeculectomy combined with cataract surgery, no previous surgical intervention). Mitomycin C appears to reduce the relative risk of failure of trabeculectomy both in eyes at high risk of failure (relative risk 0.32, 95% confidence interval 0.20 to 0.53) and those undergoing surgery for the first time (relative risk 0.29, 95% confidence interval 0.16 to 0.53). No significant effect on failure was noted in the group undergoing trabeculectomy combined with cataract extraction. Mean intra‐ocular pressure was significantly reduced at 12 months in all three participant groups receiving Mitomycin C compared to placebo. No significant increase in permanent sight threatening complications was detected but none of the trials were large enough or of sufficient duration to address the long term risk of bleb infection and endopthalmitis, which has been reported in observational studies. Some evidence exists that Mitomycin C increases the risk of cataract. The quality of trial reporting is poor in eight trials. Repeat analysis with three trials rated as low risk of bias did not yield different results.
Authors' conclusions
Intra‐operative Mitomycin C reduces the risk of surgical failure in eyes that have undergone no previous surgery and in eyes at high risk of failure. Compared to placebo it reduces mean intra‐ocular pressure at 12 months in all groups of participants in this review. Apart from an increase in cataract formation following Mitomycin C, there was insufficient power to detect any increase in other serious side effects such as endophthalmitis.
Plain language summary
Mitomycin C reduces risk of surgery failure for glaucoma but may increase risk of cataracts
Glaucoma is a serious condition caused by abnormal pressure on the eye leading to blindness. Surgery is performed to create a channel through the sclera (outer layer of the eyeball) for the fluid in the eye to drain. Sometimes scar tissue blocks this channel, pressure in the eye rises and the operation fails. Mitomycin C is a drug used during the initial stages of surgery to prevent the conjunctiva healing onto the sclera. The review of trials found Mitomycin C reduces the risk of surgery failure but adverse effects include an increased risk of cataracts.
