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Canaloplasty shows promising results at 3 years
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Canaloplasty provides reasonable control of IOP, a low complication rate and significantly less postoperative management compared to filtering procedures, according to a surgeon.
“Good outcomes depend on proper patient selection and mastery of the multiple surgical steps,” Brian Flowers, MD, said at the annual joint meeting of Ocular Surgery News and the Italian Society of Ophthalmology in Rome.
Canaloplasty (iScience) is a nonpenetrating glaucoma surgery in which a suture is placed into a dilated Schlemm’s canal. Aqueous drainage is directed through the normal outflow system without creating a filtering bleb.
“Ideal candidates are patients in whom we want to avoid hypotony, such as high myopes or people on anticoagulants, as well as patients who need a rapid visual recovery and patients who can tolerate IOP in mid- to high teens, which in my practice is most people,” Dr. Flowers said.
Patients who have had previous incisional surgery that violated the angle should be excluded. Little is known about canaloplasty in conditions other than primary open-angle glaucoma, such as angle closure, congenital and steroid-induced glaucoma, he said.
A prospective international study examining canaloplasty is currently ongoing. Results at 2 years were published in 2009, and 3-year results are now available for canaloplasty-only and canaloplasty combined with phacoemulsification.
“In canaloplasty-only, pressure was reduced from 23.6 mm Hg initially to 15.4 mm Hg at 3 years, and medications were reduced from 1.9 to 0.9. The phaco-canaloplasty group had a similar initial IOP, but a greater pressure reduction and a larger decrease in medication use at 3 years,” Dr. Flowers said.
To achieve these good pressure results, two conditions must be fulfilled: creating an adequate window and having proper suture tension.
According to Dr. Flowers, making an adequate window is probably the most challenging step at the beginning of the canaloplasty learning curve. A new, modified Drysdale manipulator (Rhein Medical) has simplified this step, he said.
Emerging data support a window length of 250 µm to 500 µm. After the second flap has been made, dissection is carried out gently with the Drysdale, trying to avoid ruptures.
“As you do the dissection, go broadly and laterally to fish-mouth the wound. At the end of this step, you must have discernable flow and an adequate window size,” Dr. Flowers said.
Adequate suture tension has been linked to improved outcomes in the ongoing multicenter study. Distension grade is a measure of how tight the suture is. Poor tension vs. good tension was correlated with a marginal decrease in pressure vs. a substantial decrease in pressure.
“In order to achieve proper suture tension, prior to tying the stitch, you lower the pressure to single digits. Then, instead of tying a normal 3-1-1 knot, you either do a slipknot or a 4-1-1 knot to achieve proper tension,” Dr. Flowers said.
“The results thus far provide good ground for optimism,” he said. – by Michela Cimberle
Reference:
- Lewis RA, von Wolff K, Tetz M, et al. Canaloplasty: circumferential viscodilation and tensioning of Schlemm canal using a flexible microcatheter for the treatment of open-angle glaucoma in adults: two-year interim clinical study results. J Cataract Refract Surg. 2009;35(5):814-824.
- Brian Flowers, MD, can be reached at 1201 Summit Avenue, Fort Worth, TX 76102; 817-332-2020; e-mail: bflowers@medsynergies.com. Dr. Flowers has received consulting fees from iScience.
