Two-year data from an ongoing study demonstrates the safety and effectiveness of bioreinforced cyclodialysis with scleral allograft in managing primary open-angle glaucoma (POAG) in patients undergoing cataract surgery. The data were presented at the American Glaucoma Society’s annual meeting last week in Washington, DC.
The bioreinforced cyclodialysis procedure uses the CycloPen system (Iantrek) to create a cyclodialysis cleft between the anterior chamber and the suprachoroidal space. The device then places biocompatible allograft tissue called AlloFlo to help keep the drainage pathway open, enhancing uveoscleral outflow to reduce intraocular pressure (IOP).
Significant Reduction in IOP, Medications
During Friday’s poster session, Leon W. Herndon, MD, a glaucoma specialist and professor of ophthalmology at the Duke University Eye Center in Durham, North Carolina, presented data on nearly 90 patients from the CREST clinical trial. All subjects had visually significant cataract and POAG and underwent surgical treatment with phacoemulsification followed by the bioreinforced cyclodialysis procedure, said Dr. Herndon. At 24 months, mean medicated IOP was reduced from 19.5±4.9 mmHg at baseline to 14.6±6.7 mmHg, and the mean number of IOP-lowering medications declined from 1.61±1.4 at baseline to 0.70±0.81, Dr. Herndon reported.
These figures are both statistically significant and clinically meaningful, according to Dr. Herndon, who is a consultant to Iantrek. “We showed significant IOP lowering by about 25% out to 2 years, with a significant drop in the number of medications that were required , and the safety profile was acceptable,” he said. “I’m excited about the results.”
Return to the Suprachoroidal Space
Although the conventional outflow pathway accounts for most aqueous drainage, uveoscleral drainage through a cyclodialysis cleft, or separation between the ciliary body and the scleral spur, can have a strong IOP-lowering effect, explained Dr. Herndon. “Most of the aqueous flows through the trabecular meshwork outflow system, but the unconventional pathway may be responsible for 25 to 40% of aqueous outflow,” he said.
Creating a cyclodialysis cleft to lower pressure is not a new idea. This concept was first tried more than a century ago, but outcomes were unpredictable, the risk of hypotony was high, and eventually the cleft would close naturally. As trabeculectomy and other filtering surgeries were refined to offer consistent IOP control with fewer risks, cyclodialysis procedures fell out of favor.
In July 2016, the US Food and Drug Administration (FDA) approved the CyPass Micro-Stent (Alcon), a minimally invasive glaucoma surgery (MIGS) device that specifically targeted the suprachoroidal space, for use in patients with mild to moderate POAG undergoing cataract surgery. However, Alcon voluntarily withdrew CyPass from the market in August 2018, after 5-year data from the COMPASS-XT study showed a concerning level of corneal endothelial cell loss. Currently, there are no FDA-approved devices to access the suprachoroidal space.
The bio-reinforced cyclodialysis procedure addresses these concerns, said Dr. Herndon. “The CycloPen comes loaded with a precut sliver of scleral patch graft tissue, and the surgeon can direct this tissue into the cyclodialysis space,” he explained. “It serves like a spacer to keep that cyclodialysis cleft open. Because the tissue is homologous, it doesn’t react like a foreign body in the eye. There’s no inflammatory component, as was seen with previous synthetic foreign bodies such as the CyPass.”
The ab interno procedure to create the bioreinforced cyclodialysis cleft seems to have a low learning curve, said Dr. Herndon, and will be familiar to surgeons who previously implanted the CyPass device. GP
