Further understanding of Schlemm’s canal needed to improve glaucoma surgery

SNOWBIRD, Utah — The future of glaucoma surgery may involve microsurgery on Schlemm’s canal, but more must first be learned about the canal’s structure, said David Epstein, MD, speaking here at the American Glaucoma Society meeting.

Delivering the annual AGS lecture, Dr. Epstein said surgeons can improve viscocanalostomy by understanding better the functional anatomy and physiology of the lumen of Schlemm’s canal. He encouraged ophthalmologists to pursue novel approaches to surgery on the canal.

Dr. Epstein credited Robert Stegmann, MD, with reviving interest in nonpenetrating glaucoma surgery with the introduction of his viscocanalostomy technique, which involves unroofing the outer wall of Schlemm’s canal. He noted, however, that abnormalities such as ruptures can occur with viscocanalostomy, and more needs to be known about how nonpenetrating glaucoma surgery works. When the canal is unroofed, there can be a wound healing response and a collapse of tissue, he said.

“There needs to be a focus on Schlemm’s canal and circumferential therapy. Schlemm’s canal must be dilated to get circumferential flow,” Dr. Epstein said. “We need the inner wall for IOP regulation.”

He said the ability to penetrate intralumenally without totally removing the inner wall of the canal could be key to a better surgery. Medications currently under investigation will “make the inner wall leakier,” he said. New instruments will also be needed to facilitate surgery on the canal.