American Academy of Ophthalmology
Canaloplasty is the circumferential viscodilation and tensioning of the inner wall of Schlemm’s canal to treat open-angle glaucoma. First, a nonpenetrating dissection technique is used to expose Schlemm’s canal. Then a flexible microcatheter (iTrack 250A, iScience Interventional) is used to dilate the full circumference of the canal by injecting sodium hyaluronate 1.4 percent (Healon GV) during catheterization. A suture loop is then placed in the canal to apply tension to the trabecular meshwork. Lewis et al. conducted a multicenter, prospective study of this new procedure on 94 patients with an IOP of at least 16 mmHg or higher.1 Of the 74 patients who had successful tension suture placement, the mean IOP was 15.3 +/– 3.8 mmHg at one year postop, and medication use dropped to a mean of 0.6 +/– 0.9 per patient. In the suture-placement group, 60 percent of patients achieved IOP levels below 15 mmHg without medication use at one year. Data for those without suture placement were not presented.
The study researchers report that there is a learning curve with this procedure. Centers that recruited larger numbers of patients had a greater chance of successful suture placement and better results. Successful circumferential catheterization of the canal was achieved in 88 percent, while tension sutures were successfully placed in 89 percent of these.
The study represents an important advance in the evolution of nonpenetrating glaucoma surgery, but five-year follow-up results are necessary to better evaluate the efficacy of this procedure.
Lewis et al. acknowledge some of the study’s limitations, but there are many variables (suture placement vs. non–suture placement, and cataract surgery with canaloplasty vs. canaloplasty only) in the study, and it is unclear from the analysis how these variables might have affected the final outcome. Another issue of concern was the high dropout rate during follow-up, which was not addressed in the article. It is unclear what influence the data from these missing patients would have had on the statistical analysis.