October 2018: The device used in this procedure (CyPass) has been withdrawn by the manufacturer Alcon, because of concerns about its long-term safety. Further details can be found in the Voluntary Field Safety Notice issued by Alcon. Surgeons are advised not to implant this device, to return any unused devices to Alcon and to consider reviewing any patients who have already been implanted with CyPass. Therefore NICE has decided to withdraw its guidance. NICE would consider whether to issue new guidance on ab interno supraciliary microstent insertion with phacoemulsification for primary open-angle glaucoma should evidence using an appropriately CE marked device become available.