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

Abstract

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). Ophthalmology Section, Palermo University, Palermo, Italy. Prospective cohort study. 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. 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). 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.