A pressure drop

Paracelsus Medical University, Salzburg, researcher, Dr Herbert Reitsamer, talks to OT  about a new glaucoma device, Xen, to be presented by Allergan at the European Glaucoma Society Congress (19–22 June, Prague)


What type of glaucoma patient is the implant for? 

The Xen gel implant is suited for patients who cannot tolerate eye drops and have a target pressure of not less than 13 mmHg. However, considering a combination of two implants in a single eye might very well deliver pressures around 10 mmHg without additional drops. Clinical studies on this subject are pending.

The implant can be used for every patient who has a healthy conjunctiva and a target pressure lower than 13 mmHg, in combination with a single class or less of topical therapy.

What are the details of the Apex trial?

The study is a two-year prospective, non-randomised study to evaluate the Xen gel glaucoma implant.

Nineteen centres in eight countries were involved and only patients without prior glaucoma surgery – except laser trabeculoplasty – were included. 215 eyes with mild to moderate primary open angle glaucoma (POAG) were treated with an implant to reduce intraocular pressure. 111 eyes were treated with a Xen implant only and 104 eyes were treated with a combined cataract extraction plus a Xen implant.

How are the results coming along? 

The trial is still on-going and the official results of the first 12 months will be published shortly. As the primary investigator, I was involved in the analysis of the data, which provided interesting results on the efficacy and safety of the implant. In general, the data indicates high efficacy while offering very good safety. Among the minimally invasive glaucoma surgery devices, Xen seems to be one of the most efficient minimally invasive glaucoma implants in lowering intraocular pressure.

What did the patients in the trial think of the implant? 

Patients in general were happy with the implant, because overall there was a low inflammatory response, and visual acuity did not decrease following the surgery.

Why was the implant developed and how does it compare to other glaucoma surgical devices? 

The development of the implant was driven by the idea that we needed to bypass the obstacles other implants come across when they drain aqueous humour into Schlemm’s canal, such as episcleral venous pressure.

There are several other products on the market, mostly implanted in the eye in Schlemm’s canal. Xen is currently the only intraocular minimal invasive glaucoma surgical device that utilises the sub-conjunctival space for filtration of aqueous humour to lower intraocular pressure.

Whether the implant is truly more efficient than other devices remains to be analysed, and might possibly be substantiated by the final results of the Apex trial.