Glaucoma is the leading cause of blindness in the United States, according to the National Institutes of Health. An estimated 4 million Americans are affected by glaucoma. Glaucoma screenings are suggested for anyone over 40, every two to four years. A routine exam can help identify risk for glaucoma and early signs of the disease. Risk factors for glaucoma include: a family history of the disease, African Americans or Hispanic ancestry, diabetes, certain rare eye diseases and having had an eye injury or having used any corticosteroid preparation for a prolonged period.
Glaucoma is often treated with eye drops that reduce the production of fluid in the eye, or help it drain more quickly. However, when the medicines don't work -- or when patients can't remember to take them once or more daily -- surgery is an option. The traditional surgery is trabeculectomy, in which a portion of the trabecular meshwork is removed, helping to reduce the bottleneck causing elevated eye pressure. Trabeculectomy is considered the gold standard for effectiveness, but can cause infection or other complications serious enough to result in blindness.
Canaloplasty is one of the newest alternatives and involves forcing open a drainage canal, similar to what cardiologists do to unblock clogged arteries. The procedure is sometimes called "angioplasty for the eye." In canaloplasty, an incision is made in the eye and a thin catheter is inserted into Schlemm's Canal, a tube in the trabecular meshwork. Instead of a balloon, a thick clear gel is injected to open the canal. In addition, a suture, or surgical tie, is placed inside the canal and pulled tight to stretch open the trabecular meshwork, says Richard Lewis, a Sacramento, Calif., eye surgeon who serves as a consultant to iScience Interventional Corp., a Menlo Park. Calif., company that sells the catheter.
The procedure takes about a half hour and can be done under local anesthetic, typically in a hospital or outpatient surgery center with a sedative. The cost -- typically $2,500 to $3,500 -- is covered by many insurers, while others decline payment because they say there isn't yet enough evidence for the procedure's effectiveness. Serious complications are rare, but can include swelling, overly low eye pressure and blood in the eye.
Surgeons agree that canaloplasty is a safer option than the traditional surgery, but some urge caution."The results that they've published thus far show great promise," says Douglas Rhee, a glaucoma specialist at the Massachusetts Eye & Ear Infirmary in Boston. "Additional studies need to be done," he adds, including trials that compare it directly to other procedures such as trabeculectomy.
Arthur Sit, assistant professor of ophthalmology at the Mayo Clinic in Rochester, Minn. is concerned that scar tissue left from canaloplasty could make a subsequent trabeculectomy less effective. Dr. Sit prefers trabectome, which he says involves a smaller incision that is less likely to impact later surgeries.
