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Cataract Surgery Technique Affected by Tamsulosin

BETHESDA, MD, 23 November 2005 — Patients' use of an alpha-1-receptor blocker needs to be taken into consideration by ophthalmologists before cataract extraction, the U.S. distributor of tamsulosin hydrochloride said in a letter distributed Tuesday by the Food and Drug Administration.

The "Dear Doctor" letter (PDF) from Boehringer Ingelheim Pharmaceuticals Inc. said that the condition known as "intraoperative floppy iris syndrome" has been observed in alpha-1-blocker users during phacoemulsification cataract extraction, a surgical procedure in which ultrasonic vibrations are used to fragment the lens before removal. Prolapse of the iris toward the phacoemulsification incisions could complicate the surgery.

Boehringer Ingelheim distributes tamsulosin under the brand name Flomax. The drug, an inhibitor of alpha-1A adrenergic receptors, is used to treat the signs and symptoms of benign prostatic hyperplasia.

Physicians, the company stated, should ask male candidates for cataract surgery whether they have taken tamsulosin or another alpha-1-blocker. In cases where surgical candidates have at some time used an alpha-1-blocker, the company is advising ophthalmologists to prepare for "possible modifications of their surgical technique" if intraoperative floppy iris syndrome occurs.

The company said that no one has found a benefit from stopping alpha-1-blocker therapy before cataract surgery and no one has established a "definitive causal relationship" between intraoperative floppy iris syndrome and alpha-1-blockers.

Information about an association between tamsulosin exposure and intraoperative floppy iris syndrome was first publicized in January by the American Society of Cataract and Refractive Surgery. The organization issued a "physician advisory" and established a working group to investigate the issue.

Much of what is known about the association between tamsulosin exposure and intraoperative floppy iris syndrome comes from ophthalmologists John R. Campbell and David F. Chang.

Campbell first suggested the association after noticing "floppy irides" during cataract removal, according to the April issue of Cataract and Refractive Surgery Today (PDF). A review of records for 511 of his practice's surgical patients in 2003 revealed that floppy irides occurred in about 2 percent of the cases and only in patients who had taken tamsulosin.

Chang took the next step and studied 900 consecutive cataract-extraction patients without knowing their medication history before surgery. He reported that about 2 percent of the cases had a floppy iris during the surgical procedure and that 15 of the 16 patients with the problem were using tamsulosin or had taken the drug at some time in the past. Among the patients who did not have a floppy iris during surgery, no one had been exposed to tamsulosin.

Other researchers had suggested in 2003 that alpha-1A receptors mediate contraction of the iris dilator muscle.

Campbell and Chang reported their studies in the April issue of the Journal of Cataract and Refractive Surgery.

—Cheryl A. Thompson