Background: Trabeculectomy is performed as a treatment for many types of glaucoma in an attempt to lower the intraocular pressure. The surgery involves creating a channel through the sclera, through which intraocular fluid can leave the eye. If scar tissue blocks the exit of the surgically created channel, intraocular pressure rises and the operation fails. Antimetabolites such as 5-Fluorouracil (5-FU) are used to inhibit wound healing to prevent the conjunctiva scarring down on to the sclera. This is an update of a Cochrane review first published in 2000, and previously updated in 2009.
Objectives: To assess the effects of both intraoperative application and postoperative injections of 5-FU in eyes of people undergoing surgery for glaucoma at one year.
Search methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to July 2013), EMBASE (January 1980 to July 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 25 July 2013. We also searched the reference lists of relevant articles and the Science Citation Index and contacted investigators and experts for details of additional relevant trials.
Selection criteria: We included randomised trials of intraoperative application and postoperative 5-FU injections compared with placebo or no treatment in trabeculectomy for glaucoma.
Data collection and analysis: Two authors independently assessed trial quality and extracted data. We used standard methodological procedures expected by The Cochrane Collaboration. We contacted trial investigators for missing information. Data were summarised using risk ratio (RR), Peto odds ratio and mean difference, as appropriate.The participants were divided into three separate subgroup populations (high risk of failure, combined surgery and primary trabeculectomy) and the interventions were divided into three subgroups of 5-FU injections (intraoperative, regular dose postoperative and low dose postoperative). The low dose was defined as a total dose less than 19 mg.
Main results: Twelve trials, which randomised 1319 participants, were included in the review. As far as can be determined from the trial reports, the methodological quality of the trials was not high, including a high risk of detection bias in many. Of note, only one study reported low-dose postoperative 5-FU and this paper was at high risk of reporting bias.Not all studies reported population characteristics, of those that did mean age ranged from 61 to 75 years. 83% of participants were white and 40% were male. All studies were a minimum of one year long.A significant reduction in surgical failure in the first year after trabeculectomy was detected in eyes at high risk of failure and those undergoing surgery for the first time receiving regular-dose 5-FU postoperative injections (RR 0.44, 95% confidence interval (CI) 0.29 to 0.68 and 0.21, 0.06 to 0.68, respectively). No surgical failures were detected in studies assessing combined surgery. No difference was detected in the low-dose postoperative 5-FU injection group in patients undergoing primary trabeculectomy (RR 0.93, 95% CI 0.70 to 1.24). Peroperative 5-FU in patients undergoing primary trabeculectomy significantly reduced risk of failure (RR 0.67, 95% CI 0.51 to 0.88). This translates to a number needed to treat for an additional beneficial outcome of 4.1 for the high risk of failure patients, and 5.0 for primary trabeculectomy patients receiving postoperative 5-FU.Intraocular pressure was also reduced in the primary trabeculectomy group receiving intraoperative 5-FU (mean difference (MD) -1.04, 95% CI -1.65 to -0.43) and regular-dose postoperative 5-FU (MD -4.67, 95% CI -6.60 to -2.73). No significant change occurred in the primary trabeculectomy group receiving low-dose postoperative 5-FU (MD -0.50, 95% CI -2.96 to 1.96). Intraocular pressure was particularly reduced in the high risk of failure population receiving regular-dose postoperative 5-FU (MD -16.30, 95% CI -18.63 to -13.97). No difference was detected in the combined surgery population receiving regular-dose postoperative 5-FU (MD -1.02, 95% CI -2.40 to 0.37).Whilst no evidence was found of an increased risk of serious sight-threatening complications, other complications are more common after 5-FU injections. None of the trials reported on the participants' perspective of care.The quality of evidence varied between subgroups and outcomes, most notably the evidence for combined surgery and low-dose postoperative 5-FU was found to be very low using GRADE. The combined surgery postoperative 5-FU subgroup because no surgical failures have been reported and the sample size is small (n = 118), and the low-dose postoperative 5-FU group because of the small sample size (n = 76) and high risk of bias of the only contributing study.
Authors' conclusions: Postoperative injections of 5-FU are now rarely used as part of routine packages of postoperative care but are increasingly used on an ad hoc basis. This presumably reflects an aspect of the treatment that is unacceptable to both patients and doctors. None of the trials reported on the participants' perspective of care, which constitutes a serious omission for an invasive treatment such as this.The small but statistically significant reduction in surgical failures and intraocular pressure at one year in the primary trabeculectomy group and high-risk group must be weighed against the increased risk of complications and patient preference.