Transciliary filtration provides improved safety and simplicity
Procedure considered faster, more controlled than trabeculectomy
Norristown, PA—Transciliary filtration (TCF) offers an alternative for safe and effective IOP lowering in phakic primary open-angle glaucoma but with many advantages relative to trabeculectomy.
Quicker procedure Compared with trabeculectomy, TCF, or Singh filtration as it is also referred to, after its creator, is a much faster and controllable operation with a better safety profile because it nearly eliminates the risk of anterior chamber collapse, said Richard Fugo, MD, PhD, inventor of the Fugo Blade.
"One of the main limitations of trabeculectomy is that the results are uncontrollable," Dr. Singh said. "Often there is too little or too much filtration, and in the latter case, there is a risk for flat chambers. TCF addresses that problem by changing the hydrostatic dynamics of the eye in a novel way. Since aqueous drains through such a tiny pore and from behind the iris rather than from in front of it, hydrostatic force against the posterior surface of the iris is eliminated and so, too, essentially is a chance for chamber flattening."
He added that because the pore is located behind the iris, TCF is an option for treating angle-closure glaucoma as well as open-angle glaucoma.
TCF also requires a lot less surgery than trabeculectomy, he said. No scleral flap or iridotomy is needed, and the entire procedure can be completed in less than 8 minutes.
The surgery is performed using peribulbar anesthesia. It begins with creation of a 5-mm conjunctival flap. Once the flap is pulled back, the Fugo Blade fitted with a 0.5-mm diameter tip is used to ablate through the sclera to the ciliary body. This is easily identified because the base of the pit turns from white to a darkened color. The operator switches to a thin tip to create the micropore in the ciliary body. The appearance of fluid seepage signals the endpoint for the ablation, which takes several seconds.
The conjunctival flap is replaced and closed with a single suture. Postoperative care is minimal and involves only antibiotic and steroid drops.
The simplicity and predictability of this procedure are like-ly to have important implications in making cataract surgeons more likely to perform glaucoma surgery.
"Currently, the vast majority of cataract surgeons will not do trabeculectomy because it is so unpredictable," Dr. Singh said. "TCF offers a truly controlled option and so we believe it will become widely adopted. Veterinarians have already begun using TCF to control glaucoma in dogs."
The Fugo Blade creates the micropore through the sclera and ciliary body by tissue ablation, not by true cutting, using plasma energy surrounding its thin, blunt ablation filament to dissolve tissue bonds. Incision proceeds resistance-free, without damage to adjacent tissue, and with minimal bleeding.
"The Fugo Blade operates at very low energy, causes no collateral damage, and does not cauterize the vessels," Dr. Singh said. "Rather it seems microparticles, which are created as the molecular tissue bonds are disrupted, close off the capillaries while also stimulating platelet activity and coagulation to minimize ciliary bleeding."
In more than 1,000 TCF procedures performed worldwide so far, the incidence of hyphema is about 2.5% and choroidal effusion has developed at a rate comparable with trabeculectomy.
However, all of those latter cases have been successfully managed with conservative techniques.