Pharmacologic pupil dilation as a predictive test for the risk for intraoperative floppy-iris syndrome

PURPOSE: To evaluate the effect of α1-adrenergic receptor antagonists (α1-ARAs) on pupil diameter and determine whether the diameter predicts intraoperative floppy-iris syndrome (IFIS). SETTING: Ophthalmology Section, Palermo University, Palermo, Italy. DESIGN: Prospective cohort study. METHODS: Male outpatients taking tamsulosin, α(1)-ARAs, or no α(1)-ARAs having phacoemulsification were recruited. Pupils were measured 1 month preoperatively, immediately preoperatively, and postoperatively under mesopic low (0.4 lux) and high (4.0 lux) illumination after pharmacologic dilation. The IFIS severity was graded. RESULTS: Each group comprised 50 patients. Pharmacologic dilation in both α(1)-ARA groups was statistically significantly less than in the no α1-ARA group 1 month preoperatively, immediately before surgery, and postoperatively (P=.001, P<.0005, and P<.0005, respectively). The IFIS incidence differed significantly between the tamsulosin and other α(1)-ARA groups and the no α1-ARA group (P<.0005 and P=.017, respectively) and between the tamsulosin group and the other α1-ARA group (P=.027). On regression analysis, the hazard ratio for overall IFIS incidence was 3.8 in the other α(1)-ARA group (P=.012) and 10.1 in the tamsulosin group (P<.0005). Pupil size was inversely related to IFIS incidence and severity (P<.0005). A dilated pupil of 7.0 mm or smaller had 73% sensitivity and 95% specificity for predicting IFIS (P=.0001). CONCLUSIONS: Pupil dilation was inhibited by α(1)-ARAs, in particular tamsulosin. For a pupil 7.0 mm or smaller, the risk for IFIS existed regardless of α(1)-ARAs treatment, which surgeons should take into consideration.