Surgical video implanting Ahmed FP7 Glaucoma Valve

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This video shows my surgical technique for implanting the Ahmed FP7 Glaucoma Valve. I use this device when traditional glaucoma surgery such as a trabeculectomy or Optonol ExPress mini-shunt has already failed or is likely to fail to achieve adequate pressure reduction. I have noted some of the rationale for why I do certain steps the way that I do but could easily go on for many paragraphs about each step.

After instilling topical lidocaine jelly for anesthesia and placing a 6-0 vicryl traction suture (S-29 needle) in the peripheral cornea, the eye is positioned downward to expose the surgical site supratemporally. An initial incision is made in the conjunctiva and a mixture of lidocaine and bupivicaine is infused with a blunt canula into the subconjunctival space. The conjunctival peritomy is extended for the entire quadrant and dissected beyond the equator of the eye to create enough room for the drainage device. After achieving hemostasis with wet-field cautery, 8mm from the corneal-scleral limbus is marked. The Ahmed FP7 implant is primed to break the air-lock so that flow of aqueous humor after implanting will not be impeded by this. It is then positioned such that its anterior aspect is at 8-10 mm from the limbus (6-8 if nasally placed) to prevent its back edge from hitting the optic nerve if it were placed too posterior and ptosis if too anterior. 8-0 nylon sutures are used to fixate the plate of the device, positioning it between the rectus muscles so as to not impede eye movements. The tip of the tube is trimmed to 1-2mm beyond the limbus, bevelled upward to prevent iris incarceration. (If patient is pseudophakic, with an IOL in the capsular bag, and has a shallow anterior chamber, the tube could be placed between the lens implant and the iris in which case the tip would be bevelled downward.) An x-shaped stitch is then used to tie down the tube. A piece of donor sclera (pericardium, non-viable cornea, or amniotic membrane can also be used) is sutured atop the tube, again with the 8-0 nylon, along its course to prevent it from eroding through the overlying conjunctiva over future years. I have found that this technique of using a horizontal mattress radially positioned is far less likely to erode through the overlying conjunctiva in the future than if sutures are placed at each corner of the graft. The traction suture is loosened in the cornea to bring the free-end of the conjunctiva closer to the limbus and then the conjunctiva is sutured in place using 8-0 vicryl on a BV needle, with a winged suture at each anterior corner and a horizontal mattress centrally.