Is there a connection between Flomax and cataracts?

I take Flomax (tamsulosin) to manage my BPH. The commercials say something about having cataract surgery. What’s the connection between the drug and cataracts? If I’m taking  Flomax, do I have to forgo having my cataracts removed?

Kevin R. Loughlin, M.D., M.B.A., director of Urologic Research at Brigham and Women’s Hospital, says:

Flomax works by blocking certain cellular receptors, causing the smooth muscle in the neck of the bladder and the urethra to relax. As a result, urine flow improves. Although they aren’t particularly abundant, these same receptors exist elsewhere in the body, including the iris in your eye. The iris opens and closes to adjust the amount of light entering the pupil. When the receptors that control the iris are blocked, the pupil constricts.

During cataract surgery, the ophthalmologist removes the clouded lens, which sits beneath the iris inside the lens capsule (see illustration). When the pupil is small, the relatively large iris obscures the cataract. The iris can also slip out of its normal position during surgery, making it even harder for the ophthalmologist to remove the old lens and insert a new one. This condition, dubbed floppy iris syndrome, increases the chance of complications, including vision loss.

Some researchers have suggested that patients on Flomax should temporarily stop taking it several days before cataract surgery. However, the benefit of discontinuing the drug has not been proven. Instead, tell your eye surgeon that you take this drug. He or she can modify the surgery to minimize the risk of any problems.

SOURCE: Chang DF, Osher RH, Wang L, Koch DD. Prospective Multicenter Evaluation of Cataract Surgery in Patients Taking Tamsulosin (Flomax). Ophthalmology 2007;114:957–64. PMID: 17467530.

Originally published April 1, 2008; Last reviewed April 18, 2011