It has been observed that some patients undergoing cataract or glaucoma surgery, who previously or at the time of the operation had been treated with alpha-1 adrenergic receptor antagonists, in particular with tamsulosin, develop intraoperative floppy iris syndrome (IFIS). This is a form of constriction of the pupil characterised by a combination of flaccid iris, progressive intraoperative miosis and prolapsed iris. The onset of this syndrome may increase the risk of intra- and post-operative eye complications (e.g. lens loss, detached retina, endophthalmitis).
Risk of intraoperative floppy iris syndrome in patients treated with tamsulosin
Incident data |
Description |
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Case: 2025 Age group: adult Gender: male Active substance: tamsulosin Indication: benign prostatic hyperplasia ADR: Intraoperative Floppy Iris Syndrome Outcome: resolved |
Male patient, 70 years of age, who had been treated with tamsulosin for benign prostatic hyperplasia for a period of about two to three months. More than three years after stopping the treatment he underwent a cataract operation. During this operation he presented inoperative floppy iris syndrome which complicated the procedure. The patient then reported persistent vision disorders for approximately one month, which were subsequently resolved. |
Summary and recommendation
Information for healthcare professionals of medicinal products containing tamsulosin mentions the possibility of IFIS occurring during cataract and glaucoma operations as one of the known adverse reactions.
Tamsulosin binds selectively and competitively to postsynaptic alpha-1 adrenergic receptors, in particular the alpha-1A and alpha-1D subtypes, causing relaxation of the smooth muscle of the prostate and urethra. As the alpha-1A adrenergic receptor also controls the tone of the iris dilator muscle, blocking it can cause insufficient pupil dilation.
The mechanism by which tamsulosin can cause IFIS is still not fully clear. It is suggested that it may be due to a combination of inhibition of contraction of the iris dilator muscle and anatomical changes (atrophy of the iris dilator muscle), which might not fully regress after the medicinal product has been discontinued.
The time to onset of IFIS varies and the syndrome may also present in patients who discontinued tamsulosin therapy a long time previously, even several years before the surgical operation.
The risk factors of IFIS include hypertension, male gender, advanced age and the use of other medicinal products such as finasteride, sartan drugs, benzodiazepines and several antipsychotics. The risk is higher with the use of tamsulosin compared with other alpha-1 adrenergic receptor antagonists, perhaps due to its higher affinity and selectivity for the alpha-1A receptor. A minimum treatment duration of three months has also been put forward as a further risk factor.
Therefore, the surgeon should be informed of the use of tamsulosin (or other alpha-1 adrenergic receptor antagonist) in order to adapt the surgical technique as necessary. It is recommended not to start treatment with tamsulosin in patients who are about to undergo and eye operation. It has not been shown whether discontinuing the medicinal product during the weeks preceding the operation might reduce the risk of IFIS.
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