Nova Eye Medical has announced eight surgery centres across the US have commenced a prospective, randomised clinical trial to assess the efficacy and safety outcomes of ab-interno canaloplasty.
Called MAGIC – Multi-center Ab-interno Glaucoma study Investigating Canaloplasty – the single-masked 2×2 factorial trial will assess several factors that impact the clinical outcomes of ab-interno canaloplasty, including a comparison of the Nova Eye’s iTrack Canaloplasty Microcatheter with the OMNI Surgical System (Sight Sciences).
The clinical impact of the type of ophthalmic viscosurgical device (OVD) used during the procedure, and the volume of OVD delivered, will also be assessed.
According to the Adelaide medical technology company that has operations in Fremont, California, ab-interno canaloplasty will be performed as a standalone procedure to eliminate the confounding effect of cataract surgery, which has been shown to lower intraocular pressure (IOP) in some glaucoma patients.
The trial will be performed over 12 months and will enrol up to 160 patients with mild to moderate, uncontrolled primary open-angle glaucoma (POAG) on one to four medications. Patients will be randomised to the iTrack and OMNI treatment groups respectively.
Primary endpoints will include reduction in mean IOP and mean number of anti-glaucoma medications. Secondary endpoints will include surgical and postoperative complications.
Dr Shamil Patel, the trial’s principal investigator and senior ophthalmologist at Eye Physicians & Surgeons of Arizona, said the ability to deploy ab-interno canaloplasty as a standalone procedure, and in combination with cataract surgery, supported its versatility in the glaucoma treatment algorithm.
The mechanism of action of ab-interno canaloplasty, which reduces outflow resistance in all parts of the natural drainage system – the trabecular meshwork, Schlemm’s canal and the collector channels – further supports its role in the glaucoma treatment armamentarium, he said.
“Ab-interno canaloplasty is akin to cardiac angioplasty for the eye. Comprising 360° catheterisation of Schlemm’s canal followed by the delivery of OVD into the canal via a process of viscodilation, the multimodal mechanism of ab-interno canaloplasty addresses multiple points of blockage in the conventional outflow pathway,” he said.
“This makes it an effective treatment in the majority of my mild-moderate open-angle glaucoma patients, with most patients achieving post-operative pressures in the low teens,”
Removal of tissue ‘should be avoided’
In the US, both the iTrack Canaloplasty Microcatheter and the OMNI Surgical System are used by glaucoma surgeons in mild-moderate glaucoma patients. iTrack has been cleared by the Food and Drug Administration (FDA) for the indication of fluid infusion and aspiration during surgery, and for catheterisation and viscodilation of Schlemm’s canal to reduce IOP in adult patients with open angle glaucoma.
OMNI is said to be a manually operated device for delivery of small amounts of viscoelastic fluid, for example Healon Pro or Healon GV Pro (Johnson & Johnson Vision), Amvisc (Bausch + Lomb), or PROVISC (Alcon). It has been cleared by the FDA to cut trabecular meshwork tissue during trabeculotomy procedures.
To permit a true head-to-head comparison of the clinical outcomes of ab-interno canaloplasty, Nova Eye states the MAGIC Trial protocol will entail catheterisation and viscodilation only.
“Along with the other trial investigators, I am of the strong opinion that the removal of tissue should be avoided in the treatment of mild-moderate glaucoma patients, where possible,” Patel added.
“We know that glaucoma is a multifactorial disease. I want to preserve the trabecular meshwork tissue to leave us with the option to treat the patient’s drainage system again, depending on how their disease progresses. The tissue-sparing aspect of ab-interno canaloplasty does not limit us from future surgical options that rely on the presence of the trabecular meshwork.”
Clinical impact of ophthalmic viscosurgical devices
The role of OVD – a hyaluronic acid-based gel-like substance, which is delivered into Schlemm’s canal during the procedure – will also be evaluated during the trial. Specifically, the clinical impact of the of type and volume of OVD delivered will be assessed.
With iTrack, Patel said he took advantage of the capability to titrate the amount of OVD delivered, based on the patency of Schlemm’s canal.
“The more occluded the canal, for example, the more OVD that is required to break adhesions and push out herniations of the trabecular meshwork. The MAGIC Trial will elucidate whether adjustments to the volume of OVD delivery translate to improved clinical outcomes for our patients,” he said.
“We will also run a sub-analysis to assess whether there is a correlation between OVD type and clinical outcomes, with patients randomised to receive either Healon GV Pro or Healon Pro. Not only will this help to further our understanding of how viscodilation acts to reverse the pathological changes in glaucomatous eyes to improve outflow facility, but it will also enable us to evolve the treatment protocol for ab-interno canaloplasty accordingly.”
iTrack just 250 microns
Nova Eye Medical president Mr Joe Bankovich iTrack was the only device designed specifically for canaloplasty. It is also the only device cleared by the FDA for viscodilation of Schlemm’s canal in the treatment of glaucoma.
“It is easy to overlook the masterful design of the iTrack canaloplasty microcatheter,” he said.
“At just 250 microns it is equivalent to several strands of hair and yet it comprises an infusion pathway for the delivery of OVD, a fiber optic and a guide wire. Every element has been meticulously designed in order to enable 360° catheterisation of the canal and to achieve pressurised viscodilation – both of which are fundamental to the clinical success of canaloplasty.”
He said without sufficient pressure, the OVD may pass through the patent collector channels without impacting on the areas of outflow resistance.
“We know from lab testing that our iTrack Canaloplasty Microcatheter delivers more OVD into Schlemm’s canal than any other device. We also know that it does so via a pressurised mechanism, designed to pop open herniations of the collector channels. For these reasons, we consider iTrack to be the superior canaloplasty device,” Bankovich said.
“iTrack also offers additional benefits from a safety standpoint, featuring an illuminated fiber optic top. This enables the surgeon to monitor its progress through every treatment step and thus helps to safeguard against misdirection into the suprachoroidal space or the collector channels, which can cause patient discomfort.”
The company anticipates publication of the completed results in the second half of 2022. It’s also hoped the trial will provide prospective data on the efficacy and safety of iTrack in support of Nova Eye’s application before the Medicare Services Advisory Committee to have its system included in item 42504 in Australia.