Cincinnati—Tamsulosin HCl (Flomax, Boehringer Ingelheim), an alpha-1 blocker used to treat benign prostatic hyperplasia, has been implicated in the development of floppy iris syndrome during cataract surgery, according to Robert H. Osher, MD. Healon 5 (AMO) is his viscoadaptive agent (OVD) of choice to manage this challenging iris behavior during cataract surgery.
Dr. Osher recounted in an interview with Ophthalmology Times that at the American Academy of Ophthalmology (AAO) meeting in 2004, he and David F. Chang, MD, of Los Altos, CA, taught a course. Dr. Chang introduced a hypothesis that he and John R. Campbell, MD, of San Rafael, CA, developed about the behavior of an iris that is floppy and a medical history positive for prostate problems treated with tamsulosin HCl. To underscore the difficulty of these cases, Dr. Chang also reported a 12.5% complication rate of torn posterior capsules associated with the syndrome.
"I thought that this was a brilliant deductive exercise and one of the best bits of detective work that I have seen in ophthalmology," Dr. Osher said. He is professor of ophthalmology at the University of Cincinnati, and medical director emeritus of the Cincinnati Eye Institute.
"This prompted me to believe in the lethality of Flomax to the iris," he stated.
Use of tamsulosin HCl can result in poor dilation of the iris, which occurs because the drug is an alpha-1 blocker that affects the smooth muscle receptors throughout the body, Dr. Osher explained.
Tamsulosin HCl has become the favorite of urologists because other alpha-1 blockers, such as doxazosin mesylate (Cardura, Pfizer) and terazosin HCl (Hytrin, Abbott Laboratories), are less selective than tamsulosin HCl and increase the risk of postural hypotension.
In addition, the pupils of these patients are much more likely to constrict during surgery and the iris can billow and leap toward the aspiration port on the phaco handpiece or the irrigation/aspiration (I/A) handpiece because of its lack of tone.
The iris will also attempt to leap into the incision, even the stab incision, because of its sensitivity to a change in pressure gradient in the eye.
Dr. Osher initially tried to manage the floppy iris in these patients with the standard stretch technique of Luther L. Fry, MD, which he said he has always found to be effective for managing suboptimal pupils.
"However, in these cases, the Fry stretch technique not only does not work but also may be contraindicated because it further compromises the iris tone. When the OVD is injected after a stretch technique is performed, the pupil normally dilates beautifully. When the OVD is injected after the Fry stretch technique, the OVD almost blows out the iris. This is very paradoxical," he emphasized.
Dr. Chang had suggested the use of iris hooks or retractors for managing floppy iris syndrome in patients who had taken tamsulosin HCl. However, this option, although effective, is less than perfect because these devices take time to insert and can cause trauma to the iris, Dr. Osher noted.
There are pupil-dilating devices, similar to tires, on the market that are available from a number of companies. Use of these may require challenging manipulations, although they are effective. Drugs that have been attempted are intracameral phenylephrine, an idea introduced by Richard B. Packard, MD, who is in private practice in London and Windsor, England, and consultant ophthalmologist, Prince Charles Eye Unit, Windsor. Samuel Masket, MD, proposed using preoperative atropine, but this has met with mixed success, Dr. Osher noted. Even stopping tamsulosin HCl provides minimal, if any, benefit.
Healon 5 possesses certain attributes that made Dr. Osher suspect that this OVD may be helpful in patients with floppy iris syndrome.