Research Digest

■ Early Canaloplasty Data Indicate an Alternative to Trabeculectomy

Interim results of a 14-site study conducted in the United States and Germany on the efficacy of canaloplasty for the treatment of open-angle glaucoma were published in the July issue of the Journal of Cataract & Refractive Surgery. Circumferential viscodilation with a flexible microcatheter, followed by tensioning of Schlemm's canal using a suture loop, was shown to effectively lower IOP and medication use.

Richard A. Lewis, M.D., an ophthalmic surgeon in private practice in Sacramento, Calif., and the first author of the study, spoke with Ophthalmology Management about this study. "The procedure is on a learning curve," Dr. Lewis said, describing the microcatherization of Schlemm's canal and the injection of viscoelastic (in this study, sodium hyaluronate 1.4%) combined, in some cases, with the placement of a suture loop in the canal to apply tension to the trabecular meshwork. "None of the American surgeons had done this procedure before, so there was a necessary evolution in the procedure."

As the learning curve Dr. Lewis developed, the suturing became more common; patients were subsequently separated into 2 groups: In group 1 were patients who underwent viscodilation and in group 2 were patients who also had successful suture placement. Dr. Lewis and his co-authors found statistically significant differences between the 2 groups in both the lowering of IOP and the number of medications taken by patients.

Asked how the developing procedure compared with trabeculectomy, Dr. Lewis called the results "very different — it's night and day, really."

Noting the "black marks" left on trabeculectomy by the results of earlier trabeculectomy vs. Baerveldt tube trials, Dr. Lewis said, "We in the glaucoma community are desperately searching for an alternative to trabeculectomy. Trab is dependent on wound healing for success. Our procedure has no dependence on wound healing."

Dr. Lewis sees this procedure as "a frontier for work in the canal." Though the canal was identified over 100 years ago, Dr. Lewis said only now was it being targeted thanks to the rise of microcatherization. "You could never look at Schlemm's canal in live patients," Dr. Lewis said. "But with microcatherization and ultrasound imaging, we can look at it in live patients, and by catheterizing it, we can manipulate it." OM

■ AAO Study Finds Laser Useful for Macular Disease

The authors of a report by the American Academy of Ophthalmology (AAO) published in the June issue of Ophthalmology concluded that laser scanning imaging is a sensitive, specific and reproducible tool for quantifying macular thickness in patients with diabetic retinopathy and provides additional information to clinical examinations when used in patients with a macular hole.

Ingrid U. Scott, M.D., M.P.H., professor of ophthalmology and public health sciences at Pennsylvania State University, chair of the AAO Ophthalmic Technology Assessment Committee Retina Panel and a co-author of the study, told Ophthalmology Management, "The conclusion of the paper was based on a literature search of relevant studies that had been published at that time. Six published studies that provided level I evidence involved diabetic macular edema or macular holes in all cases except one, which involved cases of epiretinal membrane."

The study, the result of one of the AAO's ophthalmic technology assessments, compared OCT with two laser scanner imaging devices, the Heidelberg Retina Tomograph (HRT; Heidelberg Engineering GmbH, Heidelberg, Germany) and the Retinal Thickness Analyzer (RTA; Talia Technology Ltd., Neve-Ilan, Israel, and Marco Ophthalmic, Jacksonville, FL). The HRT, the report reads, "sequentially acquires 2-D lateral … section images along the z-axis)," while the RTA "works on the principle of slit-lamp fundus biomicroscopy," generating a topographic map of retinal thickness.

Asked about the possible efficacy of laser scanning imaging AMD cases, Dr. Scott said, "At the time our assessment was conducted, there were no published studies demonstrating level 1 evidence in patients with AMD; however, other studies with lesser levels of evidence have reported the usefulness of imaging in AMD."

"Laser scanning imaging permits objective serial quantitative measurements of retinal thickness and anatomy in myriad retinal diseases, including AMD," Dr. Scott said. "It is important to point out, however, that other imaging techniques, such as fluorescein angiography, may provide information in addition to that provided by laser scanning imaging techniques, such as information regarding diagnosis and activity of the disease, in some cases." OM