Epidemiology of IFIS & Association With Tamsulosin
The overall prevalence of IFIS in patients undergoing cataract surgery is probably around 1%. However, Chang and Campbell prospectively evaluated 900 consecutive cataract procedures and reported a 2.2% IFIS prevalence. Such discrepancies may be related to regional differences or variable prescribing practice of physicians, as well as differences in perception of IFIS signs and recognition of the syndrome by surgeons.
The association between IFIS and tamsulosin has been confirmed by several studies.[9,11,16] Incidence of IFIS among those receiving tamsulosin is reported to vary between 37.9 and 90%.[9,14–18] A further report by Pärssinen et al. also found abnormal iris behavior of at least sluggish fluttering and small pupillary diameter in 21 consecutive subjects. Poor preoperative pupil dilation has been correlated with an increased likelihood of IFIS. A recent retrospective review of 59 patients (81 eyes) taking tamsulosin at the time of surgery demonstrated that preoperative dilated pupil diameter smaller than 6.5 mm is significantly associated with IFIS (p = 0.032). It should be noted that while IFIS was classically described in males, the increased use of tamsulosin for various urological indications in females may result in more females developing IFIS in the future.
In addition to tamsulosin, IFIS has been reported with other α-1 adrenergic receptor antagonists such as alfuzosin and doxazosin.[20,21] Reports have also linked IFIS to the use of various medications that have some α-antagonist effects, such as labetalol, mianserin and some psychiatric drugs.[22–24] Nevertheless, data from four large studies demonstrated that these drugs are not strongly associated with IFIS compared with tamsulosin and that the high affinity of tamsulosin for α-1a receptors underlies the pathogenesis of IFIS.[9,14,16,25] This also concurred with a retrospective study from Canada, which demonstrated that of those patients exclusively exposed to tamsulosin or alfuzosin, 86 and 15% developed IFIS, respectively. The adjusted odds ratio for IFIS in men exposed to tamsulosin compared with alfuzosin was 32 in this study. Oshika et al. demonstrated that IFIS developed in only 19% of patients on naftopidil, a selective α-1 receptor antagonist that is mainly available in Japan with a high binding affinity to both α-1a and α-1d receptor subtypes.
Other than α-1 adrenergic receptor antagonists, Schwinn and Afshari had previously suggested that IFIS could be associated with diseases that affect the tone of iris sphincter muscle, as in diabetes mellitus and hypertension. However, a large prospective study by Chadha et al. showed no evidence that diabetes is an independent risk factor for IFIS. A recent systematic review and meta-analysis of 17,588 eyes examining the association between IFIS and other risk factors showed that IFIS was positively associated with hypertension but not with diabetes mellitus.
Expert Rev Ophthalmol. 2011;6(4):469-476. © 2011 Expert Reviews Ltd.
Cite this: Review and Update of Intraoperative Floppy Iris Syndrome - Medscape - Aug 01, 2011.