After learning about a modification of the Ahmed Glaucoma Valve implantation for glaucoma that avoids the use of donor material in favour of creating a scleral tunnel, I gave it a try. You can see Dr Gdih Gdih performing the surgery on YouTube. Here is my second attempt using a modification of this scleral tunnel technique. When I tried using a 25G needle as it appears in Dr Gdih's version, I was not able to get the tube in the eye and had to convert the tunnel to a flap. In this second attempt, I used my standard 23G needle that I have used for many years.
The main difference with this technique compared with my standard, is avoidance of donor sclera (cornea, or tutoplast) in favour of this tunnel. This also saves having to suture the tube in place since the narrow tunnel keeps it there, and no suturing of donor sclera atop the tube, so after inserting the tube, conjunctiva is closed.
The things I modified compared with how Dr Gdih shows things in his video are that I still use my standard 8-0 nylon threading the needles through the implant placement holes instead of 6-0 silk with needles cut off, the bigger bore needle for the paracentesis, and I keep the plate as far back as I have in the past to minimize risk of ptosis.
I would appreciate any comments that people may have and whether they think there are advantages to a scleral tunnel compared with a donor material technique. This also differs from the old way of just putting the tube under a trabeculectomy flap.