Abstract
Purpose :
Kahook Dual Blade (KDB) goniotomy and iStent trabecular micro-bypass device implantation are two minimally invasive glaucoma surgical (MIGS) procedures used at time of cataract extraction to reduce intraocular pressure (IOP), but there are limited head-to-head comparisons and limited long-term data regarding their efficacy. We performed a retrospective chart review to determine long-term success rates of both devices and identify variables predictive of surgical success as well as safety profiles.
Methods :
A retrospective chart review of all mild-to-moderate open angle glaucoma patients whom had cataract extraction combined with KDB or iStent with a minimum two year follow up by two surgeons. 138 eyes were treated with iStent and 50 eyes were treated with KDB. Success was defined as intraocular pressure (IOP) reduction of at least 20% of baseline IOP or reduced use of at least one IOP-lowering medication. Secondary analyses included decrease in IOP from baseline, decrease in number of IOP medications, evaluation of variables predictive of surgical success, and complication rates. Statistical analyses included paired t-test, two-group t test, Wilcoxon signed rank test, Chi-square test, and Chi-square approximation.
Results :
The groups were well balanced other than slightly larger cup-to-disc ratio in iStent group (0.55 vs 0.47, p < 0.01). Success rates for iStent and KDB at two years were 64% and 55% (p = 0.28) and at three years they were 63% and 76% (p = 0.28), respectively. At two years, IOP decreased from baseline in the iStent group (-2.8, p < 0.01) but not the KDB group (-0.9, p = 0.78), while number of medications decreased in both groups (-0.3 for iStent with p < 0.01 and -0.3 for KDB with p = 0.02). No variables were consistently predictive off success across multiple time points. KDB had a higher incidence of prolonged postoperative iritis (8% vs 0%, p = 0.01), while all other complications were similar between groups.
Conclusions :
These data suggest that overall, iStent and KDB are similar in terms of success rates at two and three years for patients with mild-to-moderate open angle glaucoma, although iStent may lower IOP slightly more than KDB. There are no variables that consistently predicted surgical success. Both devices had low complication rates. Further data with larger sample sizes should confirm these results.
This is a 2021 ARVO Annual Meeting abstract.