The Benefits of a Superonasal Corneal Traction Suture for Xen Implantation Ab Interno

Dave Woods, MD
6/10/2020

The reliability and ease of implantation of my Ab Interno Xen Glaucoma Stent procedure greatly improved when I implemented a superonasal corneal traction suture with inferior traction.

Here are the benefits experienced:

2-Handedness. The traction suture frees up one hand to allow a very effective 2-handed approach to handle and guide the Xen device during implantation. 2-handedness improves the surgeon stability and safety of the device placement, including accuracy of the angle of approach, desired tunnel length, and placement of the Xen in the subconjunctival space. 2-handed placement is safer, easier, and very reassuring in challenging cases.

Improved appropriate ocular torsion and alignment for Xen placement superiorly. Ocular torsion for a nasal rotation with the superonasal traction suture also improves ease and accuracy for achieving placement closer to the Superior 12:00 position The 12:00 limbal position is effectively rotated more into alignment with ab interno approach via trajectory of a temporal wound, a much more natural aim for surgeons.

Improved exposure of conjunctiva, even in smaller eyes. Superior conjunctival exposure becomes much less challenging, as inferior traction and rotation of the globe reveal superior conjunctiva and limbus quite nicely, even in small fissure eyes. Making every case an easier case is a good indicator you are advancing your techniques.

The time of surgery is improved. More efficient and safe also adds a safety factor for less time under sedation, less risk of anesthesia, and patients can be quite comfortable under sedation. Start to finish surgical times became as efficient as my Xen ab externo stent procedure, about 15 minutes of surgical time. I now schedule Xen implants for the same time allotment as a routine cataract.

Countertraction. The benefits of good countertraction are immeasurable when advancing the Xen injector through the angle, limbus, and scleral tunnel to get your desired tunnel length. Anecdotally, one patient with severe nystagmus receiving the Xen implantation had the eye completely immobilized and no nystagmus during the implantation due to the balanced stability of the gentle pressure of the Xen aimed superiorly and inferior force of the traction suture. The combination makes a very gentle and ease of implantation with no patient cooperation needed, and no pushing on the globe with the Vera hook. I no longer need or use a Vera Hook with the supero-nasal traction suture with inferior rotation.

Here are my current steps for implantation with a traction suture ab Interno Xen (TSAI-Xen):

1. Pre-op: Mark the limbal conjunctiva with a small dot at 12:00 superiorly, and at the temporal limbus, with a sterile marking pen. This allows one to see how much cyclotorsion occurred with sedation, and how much rotation is achieved during surgery with the supero-nasal traction suture with inferior rotation.

2. Pinch drape near the nose for clamping the suture for traction. I prefer this location near the nares, and I use a mosquito clamp during times of traction.

3. Place a superonasal traction suture with 8-0 vicryl on a spatulated needle at the limbus, with 2 mm length of the pass of the suture in mid-stroma of the peripheral cornea.

4. Apply the traction suture with inferior rotation nasally, better exposing superior conjunctiva, effecting ocular torsion with the alignment of the 12:00 position more nasal. The tightness of the traction is titrated to effect for desired hand position for implantation of the Xen, and resistance desired for counter-traction for desired tunnel length.

5. Mitomycin C is injected into intra-Tenon’s space using a 30 gauge needle, approximately 8 mm superior to the limbus, and in the desired aspects of aqueous flow. Release the traction suture.

6. Make sideport and temporal incisions, with the anterior chamber filled with viscoelastic and intracameral preservative-free lidocaine.

7. Apply the traction suture, visualize the angle with gonioprism, and place the Xen via ab interno approach to the superior angle and to subconjunctival space. Use 2-handedness with comfort and confirm placement with gonioscopy. Finish the case with anterior chamber washout of viscoelastic, verify bleb formation, and seal the corneal incisions.

Superonasal traction suture with inferior traction for ab interno Xen has made challenging cases more routine and improved the reliability of Xen placement intra-operatively. This technique can improve routine case performance and assist when implanting Xen with small eyes, difficult anatomy, poor patient cooperation during surgery, nystagmus; and when one prefers the pristine incision-free conjunctiva possible with ab interno Xen.

​​​​​​​Dave Woods MD