Efficacy and safety of subconjunctival XEN gel implantation as a solo procedure or in combination with cataract surgery for open angle glaucoma: a systematic review and meta-analysis.

Background: Since studies directly comparing XEN alone vs. XEN + PHACO are often methodologically flawed and with low sample size, we decided to perform a metanalysis and systematic review of the literature, to evaluate the efficacy and safety of XEN alone in comparison with a combined surgical procedure of XEN + PHACO. Methods: Randomized controlled trials (RCTs), non-RCTs (or quasi-RCTs) and non-comparative before-after studies, prospective and retrospective studies published between January 1, 2015 and June 30, 2020 were included. Studies with no comparative group were also included. The reduction in IOP was calculated as the difference between the values at baseline and at different follow-up times. Safety was assessed in terms of incidence of intraoperative and postoperative complications in each group. For all groups without a comparative group, a Before-After Analysis for IOP reduction and drugs reduction after 12 months of follow-up has been conducted. Results: Twenty-four studies were selected for meta-analysis (1218 eyes involved): 15 studies compared “Xen solo” versus “XEN+PHACO”, 11 studies had no comparator group (6 studied XEN alone, 5 studied XEN + PHACO). Both the systematic review and the before-and-after analysis assessed that there are no significative differences in terms of IOP reduction and drugs reduction between XEN solo and XEN + PHACO combined procedures procedures at 6 and 12 months follow-up. Conclusions: There is no significative difference in terms of IOP reduction and drugs reduction between XEN solo and XEN + PHACO combined procedures procedures at 6 and 12 months follow-up. Nevertheless, because of the possible cataractogenous effect of XEN alone procedure and considering the several benefits of Combined Surgery, it is probably recommendable to perform a combined XEN + PHACO surgery in a patient with concomitant cataracts and glaucoma.