Study investigates efficacy of MIGS after subtracting cataract surgery effect
Both iStent implantation and Kahook Dual Blade goniotomy are effective in combination with cataract surgery to reduce IOP in patients with open-angle glaucoma, according to a study.
“Studies have demonstrated that cataract surgery alone leads to a significant decrease in IOP in the long term. Our research was aimed at finding whether or not the IOP decrease created by two MIGS procedures, namely iStent and KDB goniotomy, is significant after subtracting a control group of cataract surgery alone,” Christopher McNiel, medical student at Western University of Health Sciences, Lebanon, Oregon, said at the virtual Association for Research in Vision and Ophthalmology meeting.
The iStent device (Glaukos) is inserted during cataract surgery through the trabecular meshwork to increase trabecular outflow. Kahook Dual Blade (KDB, New World Medical) goniotomy is also combined with cataract surgery and decreases resistance to aqueous outflow by excising a portion of the trabecular meshwork.
The study was a retrospective chart review of data extracted from the Epic Clarity Report and hand reviewed by the researchers for accuracy. Outcome measures were IOP and IOP-reducing medications recorded preoperatively and postoperatively at day 1, week 2 and months 1, 3 and 6.
“We included 54 control eyes undergoing cataract surgery alone, 29 cataract and KDB surgery eyes and 25 cataract and iStent surgery eyes. The IOP of the iStent group was significantly lower than control at day 1, 3 months and 6 months, while the IOP of the goniotomy group was only significantly lower than control at day 1. A trend towards greater reduction of medications was found with KDB at 3 and 6 months,” McNiel said.
No adverse events were reported in the iStent group. In the KDB group, one patient developed hyperemia and IOP spike necessitating later trabeculectomy.
McNiel said that both MIGS procedures affect the trabecular outflow facility and may not be efficacious when outflow impairment is due to episcleral venous pressure or the rate of aqueous formation.
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McNiel C, et al. IOP lowering with cataract surgery alone, cataract/iStent implantation, and cataract/goniotomy in glaucoma patients. Presented at: Association for Research in Vision and Ophthalmology annual meeting; June 12, 2020 (virtual meeting).