New intranalicular implant

Early results from trials of a novel intracanalicular implant (Hydrus I, Ivantis Inc) show that the device is effective at lowering intraocular pressure and reduces the need for medications in patients with primary open angle glaucoma (POAG), according to a study presented at the XXIX Congress of the ESCRS. “These early clinical results with the Hydrus are very promising and the device may provide an interesting minimally invasive alternative to other surgical modalities intended to lower intraocular pressure,†said Manfred Tetz MD, scientific director of the Berlin Eye Research Institute, who was the first European investigator to implant the device.

Prof Tetz noted that the new device fits in with the current trend towards exploring possible surgical solutions to POAG focusing on the trabecular meshwork and Schlemm’s canal.

Made from nitinol, a flexible nickel-titanium alloy used for vascular stents, the crescent-shaped, non-luminal 8.0mm long Hydrus implant is a scaffold design intended to re-establish the patient’s conventional outflow pathway through a minimally invasive, microsurgical procedure, said Prof Tetz.

“The Hydrus comes preloaded in a disposable injector system and it is implanted using an ab-interno approach through a 1.0mm to 1.5mm incision into Schlemm’s canal, which minimises trauma to the surrounding tissue,†he said.

Since glaucoma patients often have both a blockage and a collapse of the natural outflow pathway, the Hydrus device relies on a twofold mechanism of action to tackle both aspects of the problem, first creating a relatively large opening through the trabecular meshwork, and then dilating and scaffolding Schlemm’s canal to maintain a clear outflow pathway over time.

Prof Tetz’s study was carried out at six European centres on 69 patients with mild-to-moderate glaucoma, and was intended to assess the safety and efficacy of the Hydrus implant in two distinctly different surgical settings. Twenty-nine patients received the Hydrus device in conjunction with cataract surgery, while 40 patients received the device alone.

Six-month follow-up included measurements of the change in IOP and change in glaucoma medication required by the patient. In the combination surgery group, the patients’ average IOP decreased from 21.1 mmHg before surgery to 15.6 mmHg at the six-month-follow up point. The patient’s use of glaucoma medication was reduced from an average of 2.1 to 0.4 ophthalmic eye drops per patient.

In the device-only surgery group, the average IOP decreased from 21.6 mmHg before surgery to 16.9 mmHg at follow-up, and the average medication use was reduced from 1.7 to 0.6 glaucoma eye drops per patient. Furthermore, 85 per cent of patients in the combination surgery group and 70 per cent of device-only surgery patients were free of glaucoma medication at follow-up, said Prof Tetz.

“The encouraging thing is that this effect seems to be maintained over time. We now have 25 per cent of patients at the one-year follow-up mark and this relationship has not changed,†he said.

In terms of adverse events, Prof Tetz cited some issues with minor hyphaema and anterior synechiae, primarily at the port of entry of the implant, but said that there had been no problems of device migration, hypotony or corneal oedema.

Summing up, Prof Tetz said that the Hydrus implant had shown its effectiveness at lowering IOP while also reducing the patient’s medication burden. He added that further results and studies were needed to confirm the effects of the procedure with and without combination cataract surgery over a longer follow-up.