Abstract
Purpose:
To perform a systematic review and meta-analysis to evaluate and quantify the effect and safety of iStent alone without concurrent phacoemulsication.
Methods:
Systematic review was conducted by searching MEDLINE, EMBASE, CINAHL, Web of Science,Cochrane, and conference proceedings between January 1, 2000 and June 30, 2014. Records were retrieved and screened using EPPI-Reviewer 4 gateway. Meta-analysis was completed using STATA v. 13.0. For continuous scale outcomes, standardized mean difference (SMD) was calculated as the effect size. To test heterogeneity, statistics, Z-value, and χ2 statistics was computed. Based on heterogeneity, fixed-effect and random-effect models were developed. Sub-group analysis was performed based on the number of iStents implanted in an eye and the follow-up period to assess the influence on post-operative intra-ocular pressure (IOP) and number of topical glaucoma medications.
Results:
Our search strategy identified 105 records from published literature and 9 records from grey literature. Eight studies (272 subjects) of iStent were included for quantitative synthesis. Meta-analysis results showed significant reduction in the post-operative IOP (SMD = -2.05, 95% CI: [-2.53, -1.57]) and topical glaucoma medications (SMD = -1.43, CI: [-1.92, -0.95]) after iStent implantation. Maximum reduction in IOP occurred at 6 to less than 12 months (SMD = -2.64, CI: [-3.36, -1.92]). IOP decreased with the number of iStents implanted, IOP decrease post one iStent was (SMD=-1.91, CI:[-2.14, -1.14]), post two iStents (SMD = -2.39, CI: [-4.09, -0.69]), and post three iStents (SMD = -4.26, CI: [-5.18, -3.33]). Decrease in topical glaucoma medications also correlated with number of istents implanted, with one iStent it was (SMD = -1.25, CI: [-1.94, -0.56]), with two iStents it was (SMD = -1.88, CI:[-2.20, -1.56]), and with three iStents it was (SMD = -2.00, CI:[-2.62, -1.38]). Most commonly reported complications post istent surgery is istent occlusion, iStent malposition, and hyphema although rate of occurrence differences depending on the study.
Conclusions:
iStent alone without concurrent phacoemulsification is effective in both lowering IOP and in reducing dependency on glaucoma medications. Both IOP decrease and decrease in number of glaucoma medications correlates with the number of iStents implanted. There is lack of studies on complications post IStent insertion.