Combined cataract surgery, canaloplasty sustains IOP, medication reduction at 3 years

Combined surgical procedures had better pressure-lowering effects than previously reported for phaco alone.

Bradford J. Shingleton

Performing canaloplasty in conjunction with cataract surgery can help lower IOP and reduce medications, with a learning curve that can be eased by incorporating the procedure into traditional trabeculectomy techniques, a surgeon said.

The additional surgical option grants surgeons another treatment choice for open-angle glaucoma patients, offering lowered IOP and a reduced complication profile, Bradford J. Shingleton, MD, OSN Glaucoma Board Member, said in an interview with Ocular Surgery News.

“What canaloplasty does is enable us to individualize our treatment recommendations for a patient much more,” he said.

He said that medication is effective as first-line treatment, but the cost of medicine for the chronic disease, as well as serious compliance issues with drug use, have rendered canaloplasty (iScience) a possible alternative to medical therapy. Trabeculectomy remains the gold standard in glaucoma surgical treatment, but it also has both short-term and long-term serious complications associated with it.

Canaloplasty has a learning curve that requires identification of Schlemm’s canal. Identifying Schlemm’s canal during traditional trabeculectomy surgery does not complicate or change the glaucoma surgical procedure, Dr. Shingleton noted.

“It’s a very effective way for one to learn canaloplasty while you’re actually doing your traditionally based trabeculectomy surgery. I strongly encourage people to incorporate this into their trabeculectomy techniques if they’re interested in canaloplasty. It becomes a very effective way to not feel like you’re locked into one procedure. It gives you options,” he said.

Study results

Dr. Shingleton and colleagues published a study in the Journal of Cataract and Refractive Surgery in 2008 that examined 1-year results of 54 open-angle eyes with an IOP of 21 mm Hg or higher that had combined phacoemulsification and canaloplasty. The procedures were performed by 11 surgeons at nine study sites. Since then, 3-year results of 21 eyes have been collected but not yet published.

In the study, the mean baseline IOP was 24.4 ± 6.1 mm Hg, and the mean baseline medications were 1.5 ± 1 per eye.

By 1 year, the mean postoperative IOP was 13.7 ± 4.4 mm Hg, and medication use was a mean of 0.2 ± 0.4 per patient. By 3 years, IOP was significantly reduced to the 13 mm Hg to 14 mm Hg range. The medication drop was sustained at 3 years.

Vision was also improved, with that improvement sustained over 3 years, as is typical after cataract surgery, he said.

There were no reports of hypotony, choroidal detachments or infection after the combined procedures. Hyphema occurred in approximately 5% of cases and cleared. There were four eyes (7%) with a pressure higher than 30 mm Hg on the first day postop, but those cases of transient pressure elevation also cleared.

One patient had a Descemet’s tear and one patient had an iris prolapse, which did not affect vision.

Dr. Shingleton said the results show that combined cataract surgery and canaloplasty can offer patients a safe surgical option in which IOP can be lowered more significantly than with cataract surgery alone while also providing a reduced medication burden. The study’s 3-year IOP results were somewhat similar to filtration surgery, although filtration surgery still has lower IOP capabilities. However, the complications profile of trabeculectomy renders it a “two-edged sword,” he said, with better pressure-lowering overall than combined cataract surgery and canaloplasty but at a higher risk.

“There is a role for combined cataract and canaloplasty. I am convinced of that because we’ve confirmed efficacy and pressure reduction for moderate term follow-up and significant pressure reduction on medication requirements,” Dr. Shingleton said. “When you couple this with the fact that we’re not dealing with a bleb, this is a significant step forward. So it certainly fits in the decision-making process for our patients.”

Tackling learning curve

Dr. Shingleton said some surgeons might have hesitated in performing canaloplasty because of its learning curve and the possibility that it might not lower pressure as effectively as trabeculectomy. However, results of his and his colleagues’ 3-year study of combined cataract surgery and canaloplasty have shown that the combined procedures can have significant pressure-lowering and medication-reducing effects, with the added benefit of conversion to trabeculectomy if necessary.

He performs a filtration procedure by first identifying Schlemm’s canal, which has assisted him in becoming proficient at the key aspect of performing canaloplasty. He said doing so provides an effective technique for learning canaloplasty.

“In effect, it’s a seamless transition for me from trabeculectomy to canaloplasty because I actually incorporate deep scleral flap mobilization and unroofing of Schlemm’s canal in my routine trabeculectomies. If I am doing a trabeculectomy, I just lay the deep scleral flap down and go ahead with my regular trabeculectomy procedure,” he said. “If I’m doing a canaloplasty, I cannulate Schlemm’s canal, excise the deep flap and suture the superficial flap.” – by Erin L. Boyle

Reference:

• Shingleton B, Tetz M, Korber N. Circumferential viscodilation and tensioning of Schlemm canal (canaloplasty) with temporal clear corneal phacoemulsification cataract surgery for open-angle glaucoma and visually significant cataract: one-year results. J Cataract Refract Surg. 2008;34(3):433-440.

• Bradford J. Shingleton, MD, can be reached at Ophthalmic Consultants of Boston, 50 Staniford St., Suite 600, Boston, MA 02114; 617-367-4800; fax: 617-589-0552; e-mail: bjshingleton@eyeboston.com.