A nested case-control analysis 1 included 96,128 men aged 66 years or older who had cataract surgery. According to data from the drug benefit database, 3550 patients presumably had recent (within 14 days) exposure to tamsulosin, and 7428 had recent exposure to other alpha-blockers (alfuzosin, doxazosin, prazosin, terazosin). 280 out of 284 men who had an adverse postoperative event (vitrectomy, vitreous aspiration or injection, dislocated lens extraction, or air or fluid exchange) were matched with 1102 controls according to age, surgeon, and year of surgery. Adverse events were more common among patients with recent tamsulosin exposure (21 case patients (7.5%) vs 30 control patients (2.7%), OR 2.33, 95% CI 1.22 to 4.43, NNH = 255) but not among patients with recent exposure to other alpha-blockers (21 case patients (7.5%) vs 88 control patients (8.0%), OR 0.91, 95% CI 0.54 to 1.54).
At least 10 studies have observed an association between tamsulosin use and floppy iris syndrome during cataract surgery. In a prospective cohort study on 774 patients the incidence of intraoperative floppy iris syndrome (IFIS) was 1.6%, and IFIS was seen in 14 of the 18 eyes of patients using tamsulosin (77.8%) 2.
Comment: The quality of evidence is upgraded by large magnitude of effect.
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