Most Bilateral Laser Iridotomy Patients Don't Require Meds

Miriam E. Tucker

March 06, 2014

WASHINGTON, DC — The majority of patients don't require glaucoma medications before or after undergoing bilateral laser peripheral iridotomy, an analysis of a managed care database suggests.

However, patients who require medications before the procedure are more likely to require them after. Patients who are older are also more likely to require medications after the procedure, as are those who are black.

"This can help physicians educate and counsel patients about the effectiveness of this procedure and the chances they will require additional medical or surgical interventions after laser peripheral iridotomy," said Surbhi Bansal, MD, clinical lecturer and glaucoma fellow at the Kellogg Eye Center, University of Michigan, Ann Arbor.

She presented the findings here at the American Glaucoma Society 24th Annual Meeting.

In addition to emergency use of iridotomy for the treatment of acute-angle closure crisis, the American Academy of Ophthalmology recommends the procedure for patients with primary-angle closure, angle-closure glaucoma, and suspected angle closure.

During the past 60 years, as the indications for iridotomy have increased, so has its overall use, said Dr. Bansal.

Major concerns about the procedure are its effectiveness in resolving the acute-angle process completely and whether some patients continue to be at risk for glaucoma from chronic-angle closure that persists even after iridotomy. "This study helps quantify the need for further medical and surgical therapy in the 2 years after iridotomy," Dr. Bansal told Medscape Medical News.

Largest Outcome Study

Previous smaller studies of bilateral laser peripheral iridotomy outcomes have generated mixed results on the need for subsequent intervention. This study — of 1660 adults who underwent bilateral laser peripheral iridotomy from 2001 to 2011 — is believed to be the largest, she said.

Of the 1660, 77% did not require any topical glaucoma medications before or after the procedure.

Of the 380 patients who required topical glaucoma medications, 66% required additional medication after the iridotomy, 22% required the same number of medications before and after, and 12% required fewer medications after.

During the 2-year follow-up, 12% underwent subsequent cataract surgery — most within the first year — 5% received additional laser or incisional surgery, and 1% underwent 2 or more subsequent procedures.

On multivariable logistic regression analyses, the risk of requiring glaucoma medications rose by 19% with every 5 years of increased age. Black patients had a 2.3-fold greater risk of requiring medications than white patients (P = .03), and those requiring medications before the procedure had a 16.0-fold increased risk of requiring medications after the procedure.

 
There are a lot of people doing iridotomy on folks who don't necessarily meet the criteria.
 

"We suspect that blacks are more likely to require glaucoma medications after laser peripheral iridotomy because they are more likely than whites to have a component of chronic-angle closure," Dr. Bansal told Medscape Medical News. "If the drainage system is blocked by scar tissue from chronic-angle closure, the eye pressure tends to continue to be elevated following iridotomy, requiring additional interventions. Other studies have reported higher rates of chronic angle-closure glaucoma in blacks relative to whites."

Sex, income, and educational level were not associated with additional medical or surgical interventions, she reported.

The lack of information about the patients' diagnoses is a limitation of this study. "We have no idea if these patients really had narrow angles," said session moderator Carla Siegfried, MD, from the Department of Ophthalmology and Visual Sciences at Washington University in St. Louis, Missouri.

"There are a lot of people doing iridotomy on folks who don't necessarily meet the criteria. It's very gray," she noted.

Dr. Bansal acknowledged that "one of the limitations of our study is that we were restricted to data obtained from billing records. We did not have some key clinical information, such as the level of eye pressure or the best corrected visual acuity before and after iridotomy. In the future, we hope to get access to registry data or data from other sources to evaluate the impact of iridotomy on those and other parameters."

Still, Dr. Siegfried said the study is a "great statistical analysis." The fact that most patients who required medications prior to the procedure needed new or additional medications afterward highlights the fact that, in many cases, laser peripheral iridotomy "is not a cure," she noted.

Dr. Bansal has disclosed no relevant financial relationships. Dr. Siegfried has received grant support from the National Eye Institute and Alcon, and will soon be a consult/lecturer for Allergan.

American Glaucoma Society (AGS) 24th Annual Meeting: Abstract 28. Presented March 1, 2014.

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