Moran CORE

Glaucoma Ahmed Tube Shunt

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Title: Glaucoma Ahmed Tube Shunt
Author (s): Russell Swan, MD; Craig Chaya, MD
Date: 7/18/2016
Keywords/Main Subjects: Glaucoma; Tube Shunt
Secondary CORE Category: Glaucoma / Surgical Therapy for Glaucoma
Diagnosis: Glaucoma; POAG
Brief Description: This video demonstrates a standard surgical technique for Ahmed tube shunt at the University of Utah Moran Eye Center with Dr. Craig Chaya. Below is our standard protocol:

1. Mark the superior and temporal conjunctiva
2. Perform conjunctival dissection and ensure carried to bare sclera. Relaxing incisions should be made at 12 and 3 oclock (left eye) and 12 and 9 oclock (right eye)
3. Blunt dissection into superior temporal subconjunctival space to create space for placement of shunt
4. May use brimonidine soaked sponge for additional hemostasis
5. Isolate lateral and superior rectus muscles and mark insertions
6. Prime valve using 27 gauge cannula and tying forceps
7. Deliver Ahmed plate into the superior temporal sub-Tenons space
8. Mark sclera 7.0mm posterior to the limbus
9. Pass 7-0 vicryl suture partial thickness through eyelet holes at anterior edge of place of tube
10. Tie off tube with 7-0 vicryl suture (double loop so that the tube is not amputated)
11. Ensure no flow through the tube
12. Create wick suture through tube with 7-0 vicryl suture
13. Create fenestration in tube anterior to wick suture. These two will help with IOP control in the immediate post op time period.
14. Measure position of tube and cut bevel up with scissors
15. Bend 23 gauge needle to use for entering the anterior chamber
16. Mark 3.0mm posterior to the limbus in the location you wish the tube to enter (preferably superior)
17. Create temporal paracentesis to have access to reform AC as needed
18. Initiate partial thickness scleral tunnel with 23 gauge needle and rotate eye into neutral position. Try to enter the ac just anterior to the iris root so that the tube will not be against the cornea
19. Flare scleral tunnel edge upon exit to make passage of tube easier
20. Pass tube into scleral tunnel and into AC
21. Use 7-0 vicryl suture to secure tube location with ‘X’ stitch
22. Measure patch graft material and cut to size
23. Secure anterior edge of patch graft with 7-0 vicryl suture
24. Mobilize conjunctiva and Tenon’s over the tube and plate
25. Close conjunctiva:
    1. Start with buried horizontal matress suture. Ensure episcleral bite to help prevent flap from slipping.
    2. Cut short end of suture and then use a running suture to close the relaxing incision
    3. Close the second relaxing incision in a similar fashion
    4. This can be done with the same 7-0 vicryl suture or a 10-0 vicryl suture

Tube Shunt Post-Op Guidelines

Drops:

• Continue aqueous suppressants to keep IOP as low as possible in order to blunt hypertensive phase. If IOP below 10mmHg then OK to stop them until IOP rises.
• Avoid prostaglandins after tube surgery (can increase inflammation around plate and promote encapsulation)
• Use Pred q2hrs while awake for the first 2-3 weeks then begin tapering. Taper off steroids after 6-7 weeks. Prolonged use may paradoxically promote more encapsulation and cause steroid response
• Okay to use topical and oral NSAIDs if additional inflammatory control needed
• Okay to use short course of oral Prednisone (Medrol dose pack) to help with inflammatory control in certain patients
• Antibiotic QID for 7 days and then stop

Visits:

• Recheck POD#1, POW#1, and every 2 weeks until 2 months post-op assuming all is stable
• Make sure pt returns for a visit when ligature opens up (~6 weeks post-op) to see how low IOP is and make sure chamber has not shallowed too much

Misc:

• Okay to use oral NSAIDs to control hypertensive phases
• Consider tapping blebs over plate to reduce hypertensive phase
• Tube will NOT be fully flowing until ligature suture dissolves around 6 weeks post-op
  • Fenestrated tube in front of the ligature suture will provide early filtration and IOP control

Format: video
Faculty Approval by: Craig Chaya, MD
Identifier: Moran_CORE_21536
Copyright statement: Russell Swan, MD, ©2016. For further information regarding the rights to this collection, please visit: http://morancore.utah.edu/terms-of-use/
Attribution/citation suggestions:
Swan, R and Chaya, C. Glaucoma Ahmed Tube Shunt. Moran CORE. Available at: http://morancore.utah.edu/section-14-ophthalmic-surgery/glaucoma-ahmed-tube-shunt/. Accessed July 27, 2016.