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iStent inject shows long-term efficacy in variety of glaucoma cases
Sustained effects on IOP and significant medication reductions were reported in a real-world prospective study at 3 years.
Implantation of a trabecular micro-bypass stent in patients with all types of glaucoma and moderate to severe glaucoma damage showed long-term efficacy and safety in a real-world, prospective, nonrandomized study at the University of Heidelberg, Germany.
Patients were divided into two cohorts and received the iStent inject (Glaukos) in combination with cataract surgery or as a stand-alone procedure.
“We included nearly all patients referred for surgery to our hospital if they were anatomically suitable to undergo this type of implant. We had patients with primary open-angle glaucoma, pseudoexfoliation glaucoma, narrow angle and secondary glaucoma with cup-to-disc ratio up to 0.9 and progressive visual field loss despite multiple medications. About half of the patients had undergone previous glaucoma surgery,” Fritz H. Hengerer, MD, PhD, told Ocular Surgery News.
All surgical procedures were carried out by a single surgeon, who injected two preloaded stents ab interno into Schlemm’s canal, approximately 2 clock hours apart. In patients undergoing cataract surgery, the stent procedure followed phacoemulsification and IOL implantation.
“It is a very straightforward and fast procedure, minimally traumatic, with an easy follow-up, comparable to cataract surgery. Patients take eye drops for a few weeks after surgery, and no weekly controls are necessary as you do after trabeculectomy because there is no risk of fibrosis and recovery is fast. It is easy to reach the Schlemm’s canal and place the stents, and you can immediately see the success of your surgery. As you see blood coming out of the stent, you know you have made the connection with the collector channels and can tell your patients that you have placed the stent successfully,” Hengerer said.
Stable IOP lowering, reduced medications
Results at 3 years in both groups showed stable lowering of IOP by 37% in the combined group and by 42% in the stand-alone group. Nearly all eyes had IOP less than 18 mm Hg, and 70% achieved IOP less 15 mm Hg. Medication use decreased significantly, with more than half of the eyes becoming medication-free.
“Preoperatively, the burden of multiple medications was substantial. More than two-thirds of the patients were on three to five medications, and only one eye was medication-free. After surgery, medication use was reduced to one drop per day, mostly of a prostaglandin analogue in the evening. This greatly enhanced compliance and quality of life, taking away the fear of going blind,” Hengerer said.
In the combined group, IOP reduction was approximately two to four times greater than the reduction expected with cataract surgery alone. The authors noted that 36-month outcomes were comparable in the two groups, “since the IOP-reducing effect of cataract surgery is known to be temporary and thus would be unlikely to persist through the month 36 visit.”
A safe, natural flow
“We were very happy to get nearly all our patients back to the hospital for an examination at 3 years. Even 4-year data are available, and we still see that there is no rise of IOP over time,” Hengerer said.
In addition, data were reassuring about long-term safety. The location of the iStent inject along the conventional outflow pathway preserves this implant from the complications that caused the withdrawal of the CyPass micro-stent (Alcon) from the market.
“The suprachoroidal pathway does not exist anatomically. It is created during surgery since there is no cleft between the sclera and choroid. The CyPass affected the endothelium in many cases due to misplacement but also to the structure of the stent, which could touch the endothelium even when right in place. Choroidal bleeding and detachment could occur in the long term, and data showed that fibrosis was making the stent ineffective at 3 years in some cases. These potential events must be considered when addressing that way of outflow,” Hengerer said.
No adverse events were reported during implantation of the iStent inject, nor were any long-term complications such as endothelial cell loss, corneal damage or iris damage.
“I would like to encourage many more surgeons to get informed about this option, particularly cataract surgeons when they deal with glaucoma patients. They should consider implanting the iStent inject at the end of the operation to lower IOP regardless of what the optic disc looks like. It does no harm and may reduce lifelong drug usage, improving eye comfort and quality of life,” Hengerer said.
Study results may also encourage consideration of the iStent inject in cases that are usually not an indication for other MIGS procedures.
“Specifically, in refractory eyes that have progressed in spite of previous more invasive surgery,” he said. – by Michela Cimberle
- References:
- Hengerer FH, et al. Adv Ther. 2019;doi:10.1007/s12325-019-00984-9.
- Hengerer FH, et al. Ophthalmol Ther. 2018;doi:10.1007/s40123-018-0152-8.
- For more information:
- Fritz H. Hengerer, MD, PhD, can be reached at Buergerhospital Frankfurt, Germany; email: f.hengerer@buergerhospital-ffm.de.
Disclosure: Hengerer reports he has received travel support, research grants and lecture fees from Glaukos.