Model S2 - Glaucoma Drainage Device with Valve
Glaucoma Valve Specifications

Model S2 Features:

  • Immediate reduction of intraocular pressure
  • Unique, non-obstructive valve system to prevent excessive drainage and chamber collapse
  • Implanted in a single-stage procedure
  • Eliminates drainage tube ligature sutures, "rip-chord" sutures, and occluding sutures
  • MRI safe

Valve/Plate Specifications:

  • Thickness: 1.6mm
  • Width: 13.0mm
  • Length: 16.0mm
  • Surface area: 184.0mm2

Tube Specifications:

  • Length: 25.4mm
  • Inner diameter: 0.305mm
  • Outer diameter: 0.635mm

Materials:

  • Valved plate body: medical-grade polypropylene
  • Drainage tube: medical-grade silicone
  • Valve: medical-grade silicone, elastomer membrane
  • Valve Casing: medical-grade polypropylene

Ordering Info:

Model S2 - Ahmed Glaucoma Valve


Product Brochure:


Surgical Procedure:

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Step 1.
Prime the Valve
The implant should be examined and primed prior to implantation. Priming is accomplished by injecting 1cc balanced salt solution or sterile water through the drainage tube and valve, using a blunt 26 gauge cannula.

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Step 2.
Form a Pocket
A fornix-based incision is made through the conjunctiva and Tenon's capsule. A pocket is formed at the superior quadrant between the medial or lateral rectus muscles by blunt dissection of Tenon's capsule from the episclera.

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Step 3.
Insertion of the Valve
The valve body is inserted into the pocket between the rectus muscles and sutured to the episclera. The leading edge of the device should be at least 8-10mm from the limbus.

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Step 4.
Trim the Tube
The drainage tube is trimmed to permit a 2-3mm insertion of the tube into the anterior chamber. The tube should be bevel cut to an anterior angle of 30 degrees to facilitate insertion.

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Step 5.
Making the Tube Track
A paracentesis is performed, and the anterior chamber is entered at the limbus with a sharp 23 gauge needle, parallel to the iris. Caution: Care must be taken to insure that the drainage tube does not contact the iris or corneal endothelium after insertion.

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Step 6.
Insertion of the Tube
The drainage tube is inserted into the anterior chamber approximately 2-3mm, through the needle track and parallel to the iris. The leading edge of the device should be 8-10mm from the limbus.

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Step 7.
Cover the Tube with Tissue
The exposed drainage tube is covered with donor sclera, pericardium, or cornea allograft which is sutured into place and the conjunctiva is closed.

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Note: Step 7. (Alternate)
Scleral Flap
As an alternative to Step 7, a 2/3 thickness limbal-based scleral flap may be made. The tube is inserted into the AC through a 23 gauge needle puncture made under the flap. The flap is sutured closed.

Disclaimer

The steps illustrated here are intended as a guideline only, and do not represent recommended treatment for any particular patient. The use of any specific surgical technique or maneuver is at the sole discretion of the surgeon. Surgeons should be familiar with the use of glaucoma drainage devices and post-operative care considerations before implanting any drainage device. Reference papers and surgical video tapes are available upon request.

Frequently Asked Questions:

Question: What are the indications for use of the Ahmed Glaucoma Valve?
Answer: The valve is used in all types of refractory glaucoma, specifically in neovascular glaucoma, primary open angle glaucoma unresponsive to medication, congenital or infantile glaucoma, and refractory glaucomas resulting from aphakia or uveitis.


Question: How is the Ahmed Glaucoma Valve primed?
Answer: The implant should be examined and primed prior to implantation. Priming is accomplished by injecting 1cc balanced salt solution or sterile water through the drainage tube and valve using a blunt 26-gauge cannula. Use a lot of force until liquid is seen exiting the valve.


Question: Where should the valve plate be placed?
Answer: It is necessary to place the valve as far as possible from the limbus, in-between the Tenon's capsule and sclera. (About 8-10mm away from the limbus)


Question: Where is the tube implanted?
Answer: Insert the tube into the anterior chamber, not more than 2-3mm inside. The tube should be parallel to the iris and away from the cornea.


Videos:

Model S2 Surgical Procedure


Ahmed Valve Insertion
Narrated by: Steven Cohen, MD
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