Singapore’s Health Services Agency issued an alert on a voluntary recall of the Allergan XEN glaucoma treatment system due to the presence of residual compounds from the manufacturing process.

The system is comprised of the XEN 45 gel stent preloaded into a XEN injector that is permanently implanted into the eye. The implant is designed to lower eye pressure in patients with refractory glaucoma where previous surgical treatment failed or medications alone were not sufficient.

During an in-process inspection, four units in an unreleased XEN 45 lot were observed to have trace amounts of residual polishing compounds used in the needle sleeve manufacturing process, Allergan said.