Retrospective review highlights the sustained efficacy of combination procedure.
Reviewed by Dr Karsten Klabe.
Results from 5 years of follow-up show that minimally invasive glaucoma surgery (MIGS) with simultaneous implantation of two trabecular microbypass stents (iStent Inject, Glaukos) combined with phacoemulsification is safe and provides durable moderate lowering of intraocular pressure (IOP). It also reduces the burden of topical ocular hypotensive medications, according to Dr Karsten Klabe.
Dr Klabe is in private practice at the Breyer, Kaymak and Klabe Eye Surgery Practice in Düsseldorf, Germany, and is a partner at the International Vision Correction Research Centre of the Heidelberg University Hospital. “A number of MIGS procedures are now available, and [although] they have shown encouraging initial results in pre-marketing clinical trials, data are needed to understand their long-term efficacy and safety,” said Dr Klabe.
“Our experience using combined iStent Inject implantation and cataract surgery shows that with selection of appropriate candidates, patients will rarely need further intervention for their glaucoma, and the majority can become medication-free,” he said. “Considering the latter benefit, adding the iStent Inject when patients need cataract surgery addresses the adherence issues we face when prescribing glaucoma therapies and their potential to cause ocular surface disease so that patients have a higher quality of life.”
Dr Klabe’s study of outcomes after combined cataract surgery with implantation of the iStent Inject was a retrospective review that included 164 eyes in 103 patients. The cohort had a mean age of 75.4 years and the majority were male. Primary open-angle glaucoma was the predominant diagnosis (82%) and the remaining eyes had pseudoexfoliation glaucoma (18%).
Preoperatively, the 164 eyes had a mean IOP with medication of 18.5 mmHg. The average mean deviation on the visual field was -6.19 dB MD and mean cup/disc ratio was 0.59.
Twenty-nine eyes (18%) had previously been treated with selective laser trabeculoplasty (SLT), and eight eyes had undergone previous surgery, which included placement of the Xen Gel Stent (Allergan), canaloplasty, trabeculectomy or iridotomy. All of the previous interventions were performed more than 3 months prior to the combination cataract/MIGS procedure.
Of the 164 implanted eyes, 157 had 24 months of follow-up; 129, 85 and 61 eyes were seen at 26, 48 and 60 months, respectively. Mean IOP decreased to 16 mmHg at 1 month after surgery and to 15.5 mmHg at month 6, and stabilised at that level (±0.5 mmHg) for the remaining follow-up duration.
At baseline, patients were taking a mean of 1.47 medications to lower IOP (range 0–4). Throughout follow-up, no patients were taking more than two medications and the mean of medications used daily ranged from 0.17 to 0.23 without any evidence of an increase over time.
Highlighting the safety of the combination procedure, Dr Klabe reported that there were very few complications in the series. The majority were minor and related to the MIGS procedure. They included hyphaema in 11 eyes (6.7%), persistent hypotony (IOP < 10 mmHg for more than 1 month) in two eyes (1.2%) and iris incarceration in two eyes (1.2%). In addition, there were seven cases (4.3%) of stent occlusion.
“The cases of occlusion were observed later than 3 months after surgery and were related to implantation that was too deep,” Dr Klabe said. “It is very important to hold the injector in place without pushing it forwards during implantation. However, the introduction of the iStent [inject] with a wider flange solved the risk of over-implantation.”
Data regarding the need for further glaucoma surgery provided further evidence of the efficacy of the combination surgery. Over the 5 years of follow-up, only seven eyes (4.3%) underwent a second procedure: placement of the Xen Gel Stent in three eyes, implantation of the Preserflo MicroShunt (Santen) in two eyes, SLT in one eye and cyclophotocoagulation in one eye.
The two microstents are pre-loaded in a specially designed applicator in a procedure that has a short learning curve but requires minimal additional settings and instruments, according to Dr Klabe. “When combined with phacoemulsification, the glaucoma portion of the procedure can be done either prior to or after the cataract surgery, according to the surgeon’s preference,” he said.
Dr Klabe explained that he prefers to perform the stent implantation at the end of the surgery, noting that the deep anterior chamber offers excellent visibility and lowers the risk of iris damage. “On the other hand, the main incision in my cases is only 2.2 mm and prevents the loss of [the] ophthalmic viscosurgical device and flattening of the anterior chamber,” he said. “Use of a Vold Gonioprism (Volk Optical) with retention ring may be helpful because of the low pressure on the cornea that guarantees good visibility.”