Glaucoma Implant Reduces Intraocular Pressure, Medication Burden at 3 Years

After 3 years, patients with glaucoma sustained significant reductions in both intraocular pressure (IOP) and medication when managed using a minimally invasive glaucoma surgery (MIGS) drainage device, implanted simultaneously at the time of phacoemulsification, according to a study published in Clinical Ophthalmology. These results were seen across glaucoma subtype and severity, the investigators report.

The retrospective investigation gathered data from 8 surgeons and 273 patient eyes (mean age 72.4 years), undergoing the combined cataract removal with phacoemulsification and implantation with the iStent inject^® (Glaukos Corporation) between January 2016 and February 2018. Patients presented with primary open angle glaucoma (POAG) (n=183), primary angle closure (PAC)(n=28), ocular hypertension or glaucoma suspect (n=23), normal-tension glaucoma (n=17), pseudoexfoliative glaucoma (n=7), combined-mechanism glaucoma (n=6), pigmentary glaucoma (n=6), uveitic, neovascular, or angle recession disorder (n=1 each).

Patients were followed for 36-months, and continue to be followed. The patients’ preoperative mean IOP of 16.4 mm Hg was lowered to 13.9 mm Hg by 36 months after surgery (P <.001) — and reduced IOP persisted through all time points. At 3 years, 70.3% of participants achieved IOP of 15 mm Hg or lower, compared with 49.1% who reached this level before surgery. Also, 92.7% attained IOP of 18 mm Hg or lower at 3 years, as opposed to 75.8% at baseline (both P <.001). For patients realizing these 2 IOP benchmarks both pre- and postoperatively, investigators assessed reliance on IOP-lowering drugs. Researchers report that the medication burden diminished by 64.9% for those at 15 mm Hg or lower and 71.8% for individuals at 18 mm Hg or lower.

Almost all participants (96.3%) preserved or reduced hypotensive medicine reliance. The mean preprocedure use of 1.51 medications was reduced to 0.48, a 68.5% decrease (P <.001). Subgroup analysis of the 4 most often-occurring glaucoma subtypes revealed significant reductions in IOP and meds for POAG, PAC, ocular hypertension or glaucoma suspect, and normal-tension glaucoma (all P <.05), and “revealed clinically and statistically significant IOP and medication reductions (13-22% for IOP and 42-94% for medication),” the study authors explain. 

Adverse events (AEs) during the 3-year study period were noted as mostly mild, resolving with little or no added treatment, and leaving no long-term effects. All but 3 AEs were detected in the first month after surgery. Twenty eyes needed an additional intervention such as filtering surgery or selective laser trabeculoplasty (SLT), or both. 

This data affirms previous smaller studies and case series using the same device that showed outcomes such as 3-year IOP decrease of 22% and prescription reduction by 51%, as well as research that tested iStent-alone vs cataract-iStent combination procedures and found similar IOP- and medication-reducing effects. Also, 1-year results for patients given the implant vs medical therapy show IOP of 18 mm Hg or less was reached by 92.6% of MIGS-treated patients vs 89.8% treated with medicated drops.

“The reductions in medication use sustained over this 3-year study are particularly valuable. Medication therapy is known to be effective and safe, but its utility is often limited by adherence issues,” the investigators explain. “The reductions in IOP and medication use observed in the current study equate to tangible benefits for glaucoma patients, whose ultimate goal is to achieve target IOP with the fewest medications and minimum adverse effects.”

Study limitations included the lack of a phacoemulsification control group, as well as medications prescribed by different surgeons. Also, diurnal IOP was not measured, so regression to the mean may have affected data. Conversely, “outcomes were captured in patients within real-world settings, and thus may be more directly relevant to practicing clinicians.” the researchers report. 

Disclosures: Several study authors have disclosed affiliations with the biotech, pharmaceutical, and medical device industries. Please see the original reference for complete disclosures.