MIGS study: Role of two stents for IOP

Take Home Message

Implantation of two stents (iStent, Glaukos) may be another option for controlling IOP in phakic and pseudophakic patients with open-angle glaucoma who are refractory to one anti-glaucoma medication.

Dr. Samuelson

By Lynda Charters; Reviewed by Thomas W. Samuelson, MD

Minneapolis-Implantation of two stent devices (iStent Trabecular Micro-Bypass Stents, Glaukos) may be an option for controlling IOP in phakic and pseudophakic patients with open-angle glaucoma (OAG) who are refractory to one anti-glaucoma medication, said Thomas W. Samuelson, MD.

The reduction in IOP was maintained through an 18-month, follow-up period.

“Implantation of one stent at the time of cataract surgery significantly lowered IOP and/or the need for medications. The IOP reduction was sustained in part through 5 years postoperatively,” said Dr. Samuelson of Minnesota Eye Consultants, Minneapolis, of the previous experience with the device.

More in Special Report: Novel microshunt providing dramatic and stable IOP control

About the study

The Microinvasive Glaucoma Surgery (MIGS) study then conducted a prospective analysis to evaluate the IOP and reductions in medications after implantation of two stents in phakic or pseudophakic eyes with OAG that were not controlled on one preoperative medication.

The two stents were implanted during one procedure, Dr. Samuelson noted.

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“The rationale for using two stents is pretty straightforward,” he said. “Two stents increase the likelihood that the surgical quadrant will include a major collector channel. In addition, the subjects involved in this study did not have coincident phacoemulsification.

“As such, the positive effect that phacoemulsification has on IOP is absent as compared with combined stent procedures. Two stents helps bolster the IOP-lowering effect of [the device] as a stand-alone procedure.”

Further reading: Binkhorst Lecture-Right time for MIGS

Phakic and pseudophakic patients were included in the study if they had an IOP ranging from 18 to 30 mm Hg on one anti-glaucoma medication, moderate OAG (cup-to-disc ratio [CD], ≤0.9) with no previous glaucoma surgeries, and an IOP after medication washout ranging from 22 to 38 mm Hg.

Thirty-nine eyes met the study criteria and two stents were implanted. Data from 39 patients were available at 12 months, from 37 patients at 18 months postoperatively and from 29 patients at 30 months. The mean patient age was 69.2 years. Thirty-four patients were phakic. The mean preoperative treated IOP was 20.6 mm Hg, while the mean IOP after medication was 24.1 mm Hg. The mean CD ratio was 0.7 and the mean number of preoperative medications used was 1.

NEXT: Results

Results

At 30 months postoperatively, 74% of patients (n = 31) had 20/40 or better visual acuity compared with 68% preoperatively. All patients had 20/200 or better, which was the same as the preoperative percentages.

No intraoperative adverse events occurred. Hyphema developed in one patient who required irrigation of the anterior chamber 1 week postoperatively. In 30 months postoperatively, the best-corrected visual acuity (BCVA) was 20/15. In four patients, the BCVA decreased as a result of cataract progression over 30 months, while three underwent cataract surgery and the last was 20/30 preoperatively compared with a final BCVA of 20/50.

“The mean IOP decreased to 15.1 mm Hg or less through month 30,” Dr. Samuelson said. “Three eyes required anti-glaucoma medications through month 12, and one eye needed medication through month 30.”

Ninety-two percent of 39 eyes met the primary endpoint of an IOP reduction of 20% or greater at month 12 without the need for medication. Ninety-two percent of 39 eyes also met the secondary endpoint of 18 mm Hg or less at 12 months without medication. At month 30, 97% of eyes (n = 29) had an IOP of 18 mm Hg or less.

“The mean IOP decreased through 30 months postoperatively, and the patients did not require medication to maintain the IOP with the exception of one eye,” Dr. Samuelson said. “The safety profile of the device is favorable, making implantation of two stents a viable option for patients with OAG refractory to one antiglaucoma medication.”

Dr. Samuelson cautioned that this study population included relatively mild glaucoma and patients were on just a single medication preoperatively. These data cannot necessarily be extrapolated to include more severe cases on complex drug regimens. 

Thomas W. Samuelson, MD

E: twsamuelson@mneye.com

Dr. Samuelson is a consultant/scientific advisor/investigator for Glaukos Corp.