The XEN implant is a newly developed device designed to be used as a minimally invasive surgical treatment for glaucoma patients. XEN surgery is generally performed for glaucoma patients who require further lowering of internal eye pressure (intraocular pressure) when glaucoma drops and laser therapy have failed. The aim of surgery is solely to reduce intraocular pressure, which in turn slows down the progression of vision loss caused by glaucoma. It may also reduce the need for long term eye drops for pressure control.
What is the XEN implant
The XEN implant is a small 6mm gelatinous tube made of a natural biological material called collagen. When inserted into the eye, it decreases the intraocular pressure by creating an extra drainage channel to allow constant release of additional internal eye fluid (aqueous humor) to a space under the conjunctiva (the clear membrane that covers the white of the eye) to create a ‘filtration bleb’(figure 1). This bleb may sometimes be visible in the white of the eye if the upper lid is lifted and often looks like a small “water blister” under the surface (Figure 2). From there, the fluid is drained away via the lymphatic system back into the blood stream. It does not come out onto the surface of the eye.
Figure 1
This picture demonstrate how fluid from the internal chamber of the eye is drained through the XEN implant to a space external to the eye underneath the clear membrane that normally covers the white of the eye to form a “bleb”
How is XEN surgery different from conventional trabeculectomy?
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The XEN procedure is a sutureless operation that requires far less tissue manipulation compared with conventional trabeculectomy. As such, the operating time is dramatically reduced which makes the procedure much more comfortable for patients. Post-operative follow-up also tends to be less onerous than trabeculectomy.
In terms of the efficacy of the XEN procedure in controlling glaucoma, short to medium term clinical follow-up data suggests that it is comparable to that of trabeculectomy, which up until now has been considered the ‘gold-standard’ procedure in lowering intraocular pressure in most clinical situations. However, both XEN as well as trabeculectomy surgery are subject to the risk of failure and potential complications
Figure 2
A photo of an eye that has undergone Xen surgery. The arrow highlights the location of the XEN implant which is yellow in colour and can be seen beneath the overlying transparent conjunctival membrane. The dashed line indicate the extent of the “filtration bleb” created by drainage of internal eye fluid via the XEN implant.
What are the risks?
All surgery has some risks, and any operation is not done unless the chance of benefit outweighs the risk.More common complications include transient low eye pressure or minor bleeding which can cause temporary blurring of vision. Any glaucoma surgery carries the risk of infection or bleeding in the eye which may rarely cause irreversible loss of vision, but for XEN surgery this riskis very low.
The XEN filtration bleb can become less effective if excessive scarring occurs. This may sometimes causethe bleb to fail. Medications are used at the time of the surgery and in the post-operative period during follow up to reduce scarring. The problem of scarring can occur with all types of glaucoma drainage surgery.
Summary
The XEN surgery is a recently developed surgical technique now available for the treatment of patients with moderate to advanced glaucoma who require optimisation of intraocular pressure control beyond that which drops or laser treatments can offer. It is much gentler to the eye leading to quicker recovery time compared with conventional trabeculectomy surgery. If you require any further information about XEN surgery, please discuss your questions with one of our doctors at Applecross Eye Clinic.