XEN FAQs


The XEN procedure is a minimally invasive glaucoma surgery (MIGS). It is for primary open angle glaucoma (POAG) patients not well-managed on drops and where previous medical treatments have failed.1 It is the only ab interno glaucoma procedure using the trabeculectomy outflow pathway.1,2 The XEN implant is made of gelatin. It is 6 mm long with an internal diameter of 45 μm. It is designed to help control post-operative hypotony.1,2
The XEN gel implant is made of porcine gelatin.1 This means it is biocompatible, flexible and tissue-conforming.1,3 Because the gelatin is derived from pig tissue, the XEN implant may not be suitable for some patients based on their faith, religion or beliefs. We recommend Muslim or Jewish patients contact their religious council for advice on whether the XEN implant is suitable for them from a religious perspective. It can be the case that guidance allows use for medical reasons.
The XEN gel implant creates a new outflow pathway from the anterior chamber to the subconjunctival space.1 It forms a diffuse, low-lying ‘XEN’ bleb.4 It creates a similar outflow pathway to trabeculectomy. XEN is the only ab interno procedure to do this.2
The XEN gel implant creates a diffuse, low-lying ‘XEN’ bleb.4 The XEN bleb more closely resembles healthy conjunctiva compared to a trabeculectomy bleb.5 The presence of a bleb means XEN outcomes can be modified post-operatively.6,7
The XEN gel implant is intended to reduce intraocular pressure in patients with primary open angle glaucoma where previous medical treatments have failed.1
XEN is only licensed for use in primary open angle glaucoma.1
The XEN gel implant is intended to reduce intraocular pressure in patients with primary open angle glaucoma where previous medical treatments have failed.1 It is suited to first line glaucoma surgery when a patient’s IOP is sub-optimally controlled by glaucoma drops.1,2 Patients with any of the following characteristics may be suited to XEN:
  • Need to reduce their drop burden.For example, a medication burden that may be impacting their quality of life
  • Preference, or need, to undergo cataract surgery with additional IOP lowering7
  • Manifest glaucoma progression1
  • Risk of glaucoma progression1
For more information please use the patient selection wheel on the ‘When use XEN’ page. 
The XEN gel implant can achieve significant IOP reduction and sustained mid-to-low teen IOP. In the 2-year APEX study (n=218):7
  • XEN patients achieved a mean IOP of 15.2 mmHg from a medicated baseline IOP of 21.4 mmHg (p<0.001)
  • XEN reduced drop burden. XEN patients had an average drop burden of 1.1 drops after 2 years from a baseline of 2.7 (p<0.001)
  • 44.7% of XEN patients were drop-free after 2 years (n=72/161)
 
The XEN gel implant has a favourable safety profile suited to first line glaucoma surgery where previous medical treatments have failed.1,2,7 In the 2-year APEX study (n=218):7
  • 6.4% (n=14) of patients required a secondary surgical intervention (4.1% [n=9] trabeculectomy)
  • 4.6% (n=10) of patients had hyphema
  • There was one case of endophthalmitis which occurred 15 months following treatment 

Please see the safety table on the ‘Why use XEN?’ and refer to the directions for use for specific contraindications and warnings.

The XEN procedure is a minimally invasive procedure, also known as a MIGS procedure.1 The XEN procedure is a micro-incisional, ab interno procedure and avoids conjunctival dissection.1,7 This means the XEN procedure is less invasive than trabeculectomy.6 Compared to conventional surgery the XEN implant offers faster visual recovery and fewer follow-up visits are expected.6 However, as with any surgical procedure there are risks.7 Please see the safety table on the ‘Why use XEN?’ page for more information and refer to the directions for use for specific contraindications and warnings.
The XEN gel implant forms a bleb and therefore is a ‘modifiable’ MIGS.4,6 In cases where fibrosis occurs, delicate needling around the implant tip can restore a flat bleb.6 In the 2-year APEX study the (n=218) median needling rate was 33%.7
In cases where fibrosis occurs, delicate needling around the implant tip can help restore bleb function.6 In the 2-year APEX study (n=218) the median needling rate was 33%.7
The XEN procedure is the only MIGS procedure that is both ab interno and uses the ‘gold standard’, subconjunctival outflow pathway. Therefore, compared to conventional trabeculectomy (as well as other ab externo procedures), it is less invasive and may be more suited to first line glaucoma surgery.1,2 Unlike some other MIGS devices, the XEN procedure can be performed either as a standalone procedure or combined with cataract surgery.7
The XEN procedure is a minimally invasive procedure. It is a micro-incisional, ab interno procedure that avoids conjunctival dissection.1 This means the XEN procedure is less invasive than conventional surgery. Compared to conventional surgery the XEN implant offers faster visual recovery and fewer follow-up visits are expected.6,8 
Your patients can find more information about the XEN implant from the XEN patient website
The XEN implant is made of porcine gelatin.1 Therefore, some patients may not wish to have the implant based on their faith, religion or beliefs. We recommend Muslim or Jewish patients contact their religious council for advice on whether XEN is suitable for them from a religious perspective. It can be the case that guidance allows use for medical reasons.
Please contact your local Allergan office/distributor to register your enquiry. 
The XEN implantation procedure is a short duration, micro-incisional procedure.1,4 The XEN implant is inserted into the eye with a single-use injector. The approach is ab interno through a small corneal incision. Sutures are not required.1 When experienced, XEN implantation takes approximately 10 minutes.4
When experienced, the XEN implantation procedure takes approximately 10 minutes.4
Allergan provides a comprehensive training programme for the XEN implant. When learning any surgical technique for the first time, generating predictable outcomes and minimising complications requires a structured and considered approach to training. Please contact your local Allergan office/distributor to register your enquiry. 
The XEN implant shows comparable efficacy when implanted in a standalone procedure and a procedure combined with cataract surgery. In the 2-year APEX study (n=218), patients undergoing standalone XEN procedures achieved an average 28.2% reduction in IOP from medicated baseline. Patients undergoing XEN procedures combined with cataract surgery achieved comparable IOP reduction of 27.2% from medicated baseline.7
The XEN implant is designed to stay in the eye permanently. If deemed clinically necessary, it would be feasible to remove the implant surgically.
The XEN glaucoma procedure is performed in a surgical operating room.
In most circumstances, the XEN procedure is a day patient procedure (out-patient procedure). So, most patients will be able to go home the same day. However, local practices may differ from hospital to hospital. Surgeons are advised to consider their local healthcare services and the circumstances of the patient when deciding whether patients will require in-patient care.
XEN patients should have routine follow-up appointments following XEN implantation. Typically, these occur 1 day, 1 week and 1 month after XEN implantation. Additional follow-up can be added if deemed clinically necessary and ongoing follow-up should take place once the outcome of the XEN procedure is deemed stable. IOP should be routinely measured, and bleb morphology assessed. Any measurements or observations should be determined by the doctor. Post-operative guidance on routine management can be obtained from Allergan. Please contact your Allergan XEN Surgical Specialist for further details.
1. XEN directions for use. 2016. 2. Manasses DT and Au L. Ophthalmol Ther 2016; 5(2): 135-46. 3. Vera V and Horvath C. XEN Gel Stent: The Solution Designed by AqueSys®. In J Samples and I Ahmed. Surgical Innovations in Glaucoma. Springer Media, New York, 2014. 4. Dapena CL and Ros RC. Revista Española de Glaucoma e Hipertensión Ocular 2015; 5(3): 350-7. 5. Teus MA et al. Graefes Arch Clin Exp Ophthalmol 2019; 257(5): 1005-1011. 6. Vera V et al. US Ophthalmic Rev 2018; 11(1): 38-46. 7. Reitsamer H et al. Graefes Arch Clin Exp Ophthalmol 2019; 257(5): 983-96. 8. International Glaucoma Association. Trabeculectomy. 2018. [Avaliable at: https://www.glaucoma-association.com/trabeculectomy.html (accessed: August 2019)]. 8. Szigiato AA et al. Can J Ophthalmol 2018; 53(3): 246-251.