A study recently published in the Journal of Clinical Medicine found that bio-scaffolded cyclodialysis (BSC) showed promising results in a case series involving 243 eyes. The procedure improved intraocular pressure (IOP) in 78.6% of cases without an increase in medication use. The study focused on patients with open-angle glaucoma, 79% of whom also underwent cataract surgery.
In the BSC approach, the microinvasive CycloPen system (Iantrek) is used to create a cyclodialysis pathway between the anterior chamber and the suprachoroidal space. The device then places biocompatible allograft tissue (a bio-scaffold) called AlloFlow to help keep the drainage pathway open, ensuring a controlled and stable flow of fluid.
To better understand the potential of bio-scaffolded cyclodialysis, Glaucoma Physician recently spoke with a pair of respected glaucoma specialists. Won I. Kim, MD, is the former director of the ophthalmology residency program at Walter Reed National Military Medical Center and is currently in practice with Eye Doctors of Washington in Washington, DC. Leon W. Herndon, MD, a glaucoma specialist and professor of ophthalmology at the Duke University Eye Center in Durham, North Carolina, was one of the authors of the recently published BSC study. He is a consultant to Iantrek. During our conversation, which has been edited for length and clarity, they discussed their observations about BSC and experiences with the procedure.
GP: What are your initial impressions of the BSC technique as a potential new way to manage IOP?
Dr. Kim: I started performing bio-scaffolded cyclodialysis with CycloPen maybe 6 months or so ago. I am very glad to be able to offer this to my patients as an alternative to Schlemm’s canal–based MIGS and subconjunctival surgeries like Xen gel stents (AbbVie), trabeculectomy, and tube shunts. We haven’t been able to offer anything in the suprachoroidal space since the CyPass microstent (Alcon) went off the market [in 2018].
My initial impressions: it’s still glaucoma surgery. It can work and it can fail just like all other glaucoma surgeries. It’s not perfect but a welcome addition to our armamentarium. Overall, it has greater IOP-lowering potential than other MIGS. Its safety profile is excellent, far better than trabeculectomy and glaucoma drainage implants, but it does have a little more theoretical risk than other MIGS, so it sits in the middle in terms of safety and efficacy.
It is fantastic to have this option, especially for people who’ve already failed multiple other glaucoma surgeries. You don’t need any conjunctival real estate, so it’s been wonderful to offer to patients who’ve failed trabs/tubes or people with bad conjunctiva for other reasons. People who’ve failed other MIGS now have something else to turn to before moving on to trabs/tubes.
Dr. Herndon: As surgeons, this is an opportunity to reenter the suprachoroidal space that we haven’t had access to for the past several years. This is really a novel idea, using scleral patch tissue that we use all the time in glaucoma tube surgery, to keep that space open. And [Iantrek has] really designed a unique process in the CycloPen that delivers a sliver of allograft material into the suprachoroidal space.
The paper presented the results of 240 eyes. They are short-term results, just up to 1 month, but it gives a proof of concept. It’s a small number of eyes, but I’m convinced and really excited about the ongoing data. Two-year results will be coming out soon. So it’s really early in the investigation, but the suprachoroidal space is an area that I think we as glaucoma surgeons want to reenter.
GP: In your view, are there advantages to using scleral allografts in this procedure to keep the drainage pathway open, compared to hardware implants?
Dr. Kim: CyPass got taken off the market because of endothelial cell loss, mainly in cases when the device wasn’t implanted far enough into the angle and too much of the implant was left in the anterior chamber. The rigid polyimide material presumably caused progressive endothelial trauma in these cases. The scleral allografts should, in theory, not have that effect on the endothelium, so that is a major advantage.
Implants take forever to get through the FDA approval process. Case in point, the iStar Miniject is a similar concept that is still going through trials and is likely years away from becoming readily available to surgeons in the United States. CycloPen with AlloFlow is available now. There are no hardware implants, so it got approval very rapidly.
Dr. Herndon: Many glaucoma surgeons really were happy with the results we were seeing with the CyPass, and the problem as you know with CyPass was corneal concerns. But it seems with [the BSC procedure], because the allograft is homologous to the surrounding tissue, that the rate of fibrosis will be much less and the effect on the cornea will be much less.
The AlloFlow scaffold is very similar to the surrounding scleral tissue, so it’s not going to be seen as a foreign body in the eye and inflammation will likely be less than if you had a foreign body. The results that we published showed that the rate of complications was exceedingly low and I think it’s because of that homology with the rest of the eye, so it’s not a rigid foreign body like the CyPass.
GP: How does the BSC procedure compare to other MIGS in terms of safety and efficacy?
Dr. Kim: Overall, BSC compares very favorably to other MIGS. From the efficacy standpoint, it is generally better than other MIGS. With Schlemm’s canal–based MIGS, you typically get modest IOP lowering into the mid to high teens and maybe relief from 1 medication. BSC typically can give more profound IOP lowering into the low to mid teens and sometimes even high single-digit pressures and has greater potential for decreasing medication burden.
It is vanishingly rare to see a patient on multiple glaucoma drops be able to stop all their preoperative glaucoma medications with a Schlemm’s canal–based MIGS, but with BSC you can achieve that kind of outcome a little more frequently. Overall safety is comparable to other MIGS but there is at least a small risk for hypotony, which typically doesn’t exist for Schlemm canal–based MIGS. But knock on wood, I have never seen sustained clinical hypotony with BSC that needed intervention. They have all resolved spontaneously.
Dr. Herndon: Glaucoma is a disease of long-term care, and 1 month doesn’t tell the whole story, but this early phase is usually the period when we’re most concerned about complications. If patients will have a rocky course, that will often show up within that first month. [With the BSC procedure] the rate of hypotony and hyphema was acceptably low within the first 30 days. All the complications that were noted within 30 days were self limited and resolved. We found nothing that was going to have a sight-limiting effect long term.
I really see this paper as a proof of concept that this technology seems to be safe, at least in the early phase. I look forward to longer-term studies that should be coming out in the very near future.
GP: How do you foresee bio-scaffolded cyclodialysis impacting the standard of care for glaucoma if it proves to be effective in the long term?
Dr. Kim: I see this sliding in between Schlemm’s canal–based MIGS and subconjunctival filtration surgeries (Xen gel stents, trabeculectomy, tube shunt / glaucoma drainage implants). It has the potential for more profound IOP lowering than Schlemm’s canal–based MIGS, albeit with a little more risk for hypotony. BSC is also safer from a complications perspective than Xen, trabeculectomy, and glaucoma drainage implants. They are not subject to all the bleb-related complications of Xen and trabeculectomy: dysesthesia, blebitis, etc, and they are not subject to the device-related complications of glaucoma drainage implants: corneal decompensation, erosion, diplopia, etc. So, I think it has an important niche to fill. I think the adoption with glaucoma specialists will be easier. It may be a tougher sell to a comprehensive ophthalmologist who does MIGS.
Dr. Herndon: I think it will fit in that crowded space of mild to moderate glaucoma. It is considered a MIGS procedure, and there are a lot of competing technologies in that MIGS space, but nothing right now that gives surgeons a route into the suprachoroidal space.
We’re trying to find safer and safer procedures than the traditional surgery, trabculectomies and glaucoma tubes. These work great for severe disease where you really need low pressures, but there’s a balancing act: the more advanced traditional surgeries, the more complications. I think it will offer another option as we get closer and closer to safer procedures that get these low pressures like we see with traditional surgeries.
I’m very cautiously optimistic. We’ve seen a lot of new devices come and go, but I’m really excited about the opportunity to get back into the suprachoroidal space. Anything that can be a benefit to our patients to lower the pressure safely, I’m all on board with. GP
