‘Air Xen’ technique offers alternative way to implant gel stent
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Since the Xen gel stent was FDA approved in 2016, this less invasive glaucoma surgical device has been widely used to treat refractory glaucoma, decreasing IOP by shunting aqueous to the subconjunctival space.
The device is a 6-mm long stent made of collagen-derived noninflammatory gelatin material, preloaded in a disposable injector. The straightforward procedure creates a diffuse bleb and uses mitomycin C to promote proper wound healing.
When I started using Xen (Allergan) in 2018, surgeons had already been adapting the Xen technique to meet a variety of needs. I began using an ab interno technique that I learned and adapted from Dr. Ike Ahmed called “Air Xen,” which has given me excellent outcomes as a stand-alone procedure or combined with cataract surgery. What I like about the technique is that pre-dissection to the superior conjunctival tissue where the Xen stent is to be placed aids in proper insertion into the subconjunctival space and away from Tenon’s tissue. A space that separates the conjunctiva away from Tenon’s tissue is created by injecting air subconjunctivally. When followed by an injection of cohesive viscoelastic, this separation is maintained and creates a target for the stent to be positioned. Subconjunctival dissection also allows for enhanced flow of aqueous fluid that, along with the MMC, can create a more diffuse bleb.
I recently shared a video of the Air Xen technique through my iGlaucoma YouTube channel. Here is a step-by-step breakdown.
1. Mark the eye.
Using calipers, mark the superior conjunctiva approximately 2 mm from the limbus.
2. Create the bleb.
Close to the conjunctival markings, inject air under the conjunctiva with a 30-gauge needle and then follow with viscoelastic. The air separates the conjunctiva from the Tenon’s tissue, and the viscoelastic maintains the depth of separation.
3. Make the corneal incisions and prep the anterior chamber.
Use a 20-gauge blade to create a paracentesis. Administer anesthetic and then add viscoelastic to pressurize the anterior chamber. Use a keratome blade to make an inferotemporal corneal incision to allow the Xen injector to access the anterior chamber.
Source: Constance O. Okeke, MD, MSCE
4. Implant the Xen stent, using a gonioprism for visualization.
Insert the Xen injector tip into the anterior chamber. Using a disposable gonioprism, watch as you advance the Xen injector tip, approaching the area superior to the trabecular meshwork for engagement. Using a Vera hook to infraduct the eye, insert the tip of the Xen stent through the sclera and into the subconjunctival space created by the viscoelastic. Insert the Xen stent and remove the injector slowly.
5. Verify Xen’s positioning.
Assess the angle with the gonioprism to assure that the Xen implant has at least 1 mm in the anterior chamber. Massage the Xen implant and make sure that the tip is freely mobile in the subconjunctival space.
6. Remove viscoelastic and treat wounds.
Remove the viscoelastic from the anterior chamber with balanced salt solution and hydrate the corneal wounds. Place MMC in the subconjunctival area surrounding the Xen implant and then rinse the conjunctiva.
After surgery using the Air Xen technique, recovery follows the general expectations for Xen. We monitor the bleb and see patients back for evaluation at 1 day, 1 week and then 1 to 3 weeks later, depending on how they are healing. I tend to watch a bit closer with my Xen patients compared with other MIGS patients due to the potential for scarring of the bleb. With this technique, my needling rates have decreased to around 15% to 20%. I also instruct my patients to use digital massage to help in the healing process. My patients typically achieve an IOP reduction to the single digits to low teens using one or no medications — a significant change for patients with the threat of vision loss from glaucoma who are typically on three to five medications.
- For more information:
- Constance O. Okeke, MD, MSCE, can be reached at Virginia Eye Consultants, 241 Corporate Blvd., Norfolk, VA 23330; email: iglaucoma@gmail.com; website: www.drconstanceokeke.com.
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