How MIGS with stents benefits patients with OAG

San Francisco-Patients with open-angle glaucoma (OAG) had a significant reduction in IOP and did not require anti-glaucoma medications over 1 year postoperatively when micro-invasive glaucoma surgery (MIGS) was performed, according to interim results for a MIGS study group that were reported by David F. Chang, MD.

The surgery, in which two first-generation trabecular micro-bypass stents (iStent, Glaukos) were implanted as the only treatment, appeared effective for treating the OAG, which was uncontrolled by one anti-glaucoma medication.

The MIGS study group consisted of 18 visiting international surgeons who operated on study subjects at the Malayan Center in Yerevan, Armenia. Patients who were phakic or pseudophakic (n = 39) with OAG and treated with one medication were included.

All patients had a cup-to-disc ratio of 0.9 or less and IOP between 18 and 30 mm Hg. After a medication washout period, the preoperative IOP ranged from 22 to 38 mm Hg.

All patients received two stents and were to be followed for 2 years.

Concurrent cataract surgery was not performed in the phakic patients. If the postoperative IOP exceeded 21 mm Hg, patients were restarted on anti-glaucoma medication.

The 1-year efficacy endpoints were an IOP reduction without anti-glaucoma mediations of 20% or more, an IOP of 18 mm Hg or lower without medication, and the mean change in IOP.

Follow-up evaluations throughout the 2 years of the study included:

·      Fundus and optic nerve evaluations

·      Slit lamp examination

·      Measurement of the best-corrected visual acuity (BCVA)

·      Recording of any complications and adverse events.

The mean patient age was 69.2 years and 56% were men. Eighty seven percent of eyes were phakic.

In the 39 eyes that had been followed for 1 year, compared with baseline, the mean IOP reduction overall was 44%: 67% of eyes had a reduction of 40% or more, 85% had a reduction of 30% or more, and 92% of eyes met the primary endpoint of an IOP reduction of 20% or more.

At the 1-year evaluation, 92% of eyes met the secondary endpoint of a postoperative IOP of 18 mm Hg or lower without medication and 77% of eyes had an IOP of 15 mm Hg or lower without medication.

Medication use to control IOP was unnecessary in 36 of the 39 eyes at 1 year. The IOP in these patients decreased by more than 10 mm Hg and that reduction was sustained for 1 year.

Hyphema developed in one eye 1 week postoperatively. Four eyes lost more than one line of BCVA, which was attributed to progression of pre-existing cataracts.

The BCVA remained the same or improved in 35 of the 39 eyes and at 1 year, 74% had 20/40 or better visual acuity, compared with 67% preoperatively, Dr. Chang said.

“In the United States, the (trabecular micro-bypass stent) is only approved as a combined procedure with phaco, and it is therefore hard to know how much of any resulting IOP lowering is due to the cataract surgery alone,” Dr. Change said. “This study is important because there was no concurrent cataract surgery performed, and any IOP reduction should therefore reflect the effect.”

The iStent is FDA-approved in the United States, CE marked in Europe, and has medical device approval in Canada.

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