New research published in the peer-reviewed Journal of Clinical Medicine details the use of Iantrek Inc’s uveoscleral outflow technology (CycloPen Micro-Interventional System) as an advanced surgical technique for patients diagnosed with open-angle glaucoma (OAG).
Let’s start with some background.
Historically, scleral allograft tissue has been clinically utilized during ocular surgery. It’s been reported to demonstrate “excellent safety” as a biocompatible and non-biodegradable material for reinforcing the ocular surface and protecting ocular tissues from the erosive effects of glaucoma drainage devices.
Enter interventional ab-interno delivery techniques, which, when combined with scleral allograft tissue, enable the acellular scleral matrix to provide durable and non-resorbable structural support for both glaucoma and retina surgical applications, investigators noted.
Case in point?
In surgical glaucoma, previous research has found that intraocular implantation (IOI) of a scleral allograft in the supraciliary space results in structurally enhancing and maintaining suprachoroidal outflow.
- Why: Due to the highly permeable and porous reinforcing properties of the allograft acellular matrix.
And why is scleral allograft key?
Its properties enable it to be used as a biotissue substrate for the following homologous structural components:
- Reinforcement
- Stabilization
- Reconstruction
- Stenting
Investigators have also noted that its flexibility and conformality allow for “a wide range of surface applications when used to patch grafts of a scleral wall defect.”
And the basis for this research?
Investigators used acellular homologous allograft biotissue for scleral reinforcement of the endoscleral wall of a cyclodialysis—ideally to not only “enhance the internal filtration reservoir,” but also to develop a durable conduit for uveoscleral outflow conductivity.
Keep in mind: Cyclodialysis is commonly used as an internal aqueous filtration channel to the suprachoroidal space—and has been found to effectively lower intraocular pressure (IOP) in glaucoma patients.
So what happens during bio-scaffolded cyclodialysis?
During bio-scaffolded cyclodialysis (BSC)—the procedure performed in this study—a cyclodialysis cleft forms and cuboidal allograft spacers are laterally placed to “reinforce the central filtration channel” to enable better aqueous flow through the cleft.
- This, notably, differs from standard suprachoroidal aqueous drainage devices.
Now explain how this CycloPen System is involved.
This minimally-invasive glaucoma surgery (MIGS) instrumentation is referred to as a “high-precision interventional cyclodialysis” that’s designed for the following:
- Creation of a controlled cyclodialysis
- Controlled, cannulated deployment of a cyclodialysis
- Structural material reinforcement of a cyclodialysis
At long last … talk about this study.
Investigators conducted a consecutive case series—dubbed CREST (NCT05506423)—using an initial 245 eyes diagnosed with OAG that underwent a BSC procedure using the CycloPen System for reducing IOP.
- Note: This BSC procedure involved a supraciliary implantation of an allograft scleral biotissue for reinforcement of the cyclodialysis cleft
About the participants: An estimated 300 OAG patients (aged +18) pooled from the CREST US/OUS observational, real-world evidence registries (multicenter studies) across nine surgical sites.
And the study duration?
Patients were followed for 24 months following use of the CycloPen System either:
- In conjunction with cataract surgery (phacoemulsification [phaco])
- In standalone surgery
See the implantation technique and materials that were utilized.
Note: During the study period, data was collected from preoperative, surgical procedure, and postoperative visits.
And what was measured?
The primary outcome measure involved the percentage of eyes with an IOP reduction of ≥ 20% in comparison with baseline—without the use of additional ocular hypotensive medications or IOP-lowering surgery.
- The time frame: 12 months postop
On to the findings … how many eyes were studied?
Out of the initial 245 consecutives eyes enrolled in the study, 11 were either:
- Not implanted (n = 2)
- Lost-to-follow-up by Month 1 (M1) visit (n = 5)
- Missed the M1 visit (n = 2)
- Withdrew prior to M1 (n = 2)
Thus, 234 eyes were evaluated at M1.
And the results?
The study authors stratified their findings and analyzed two subgroups out of the remaining eyes:
- Group 1 (n = 153; 63%)
- Size of the bio-reinforced cyclodialysis was < 1 clock hour
- Group 2 (n = 90; 37%)
- Eyes with cyclodialysis > 1 clock hour
To note: Though both groups’ baseline characteristics were close to the same, Group 2 demonstrated:
- Higher rate of phaco-combined intervention (87.6% vs 64.4%)
- Higher medication burden at baseline (1.7 vs 1.3, on average)
How did safety data compare?
The study authors noted intraoperative safety as “unremarkable,” with no clinically significant vision-threatening adverse events (AEs).
- Mild supraciliary blood reflex during procedure was expected
- Two cases reported (and resolved) intraoperative hyphema requiring visco-tamponade
- One case reported zonular dehiscence due to patient eye movement during part of phaco procedure
And postop safety?
Overall, the data was “characteristic of supraciliary intervention,” the authors reported.
- One serious AE was reported but determined to be unrelated to the surgery (pneumonia)
- Five cases of hyphema > 2mm were reported during Week 1 follow-up period (resolved prior to M1)
- One phaco surgery-related postop complication was reported of retained cortical segment removal
- See here for further details
How was IOP elevation postop?
Out of the 234 eyes, 11 had a postop IOP elevation > 30 mmHg and/or an increase of 10 mmHg from baseline.
Plus:
- Three eyes received additional surgical intervention for IOP control
- One eye underwent a paracentesis 2 weeks postop
- One eye received an XEN gel implant 2 months postop
- One eye was managed via YAG laser treatment with additional selective laser trabeculoplasty (SLT)
- Eight eyes were managed with topical hypotensive medications
Additionally: Four eyes of three patients developed cystoid macular edema (CME) with no significant vision loss that was resolved completely postop.
Go on …
The authors reported IOP outcomes showed improvements, with both groups demonstrating statistically significant reductions:
- Baseline mean (SD) medicated IOP*:
- Group 1: 20.4 (5.5) mmHg
- Group 2: 18.9 (6.2) mmHg
- All eyes: 19.8 (5.8) mmHg
- 30-day mean (SD) medicated IOP*:
- Group 1: 14.8 (5.4) mmHg
- Group 2: 13.2 (4.2) mmHg
- All eyes: 14.2 (5.0) mmHg
*Statistical significance of p < 0.001 in each group.
See the similar data for IOP improvements in eyes at or below 18 mmHg.
- Hint: All groups improved by +30%.
And visual acuity?
Best-corrected visual acuity (BCVA) was either maintained or improved among patients who underwent combined phaco.
- Further: No AEs or a significant >2 lines best distance-corrected visual acuity (BDCVA) loss were observed postop.
Lastly, how were refractive outcomes?
A total of 207 eyes showed postop refractive outcomes—but only seven cases (3%) demonstrated a refractive error that exceeded – 1.00 D postop.
What this means: There was no “appreciable signal of myopic shift” following the bi-enfored cyclodialysis procedure, the investigators stated.
The conclusion?
The authors concluded that the study data demonstrated a bio-reinforced cyclodialysis glaucoma procedure is capable of being “successfully combined with cataract surgery.”
- In fact, they noted: “The majority of the patients in our cohort underwent combined phaco-glaucoma intervention for mild-moderate glaucoma patients with cataract co-morbidity.”
Even better: They observed no “untoward effect” of the procedure on cataract surgery.
So what’s next?
The authors recommended longer observation and follow-up are needed to determine the “long-term efficacy and durability” of the BSC procedure, as this study mainly focused on the immediate 30-day postop period.