AIM: To determine the incidence of intraoperative floppy iris syndrome(IFIS)in patients undergoing phacoemulsification in a Chinese hospital, and to assess new risk factors and predictive factors for IFIS.

METHODS: A prospective, observational case series. In the consecutive cataract surgeries performed in one year, the medicine administration, pupil size(PS)before and after mydriasis, and signs of IFIS were recorded.

RESULTS: Totally 807 patients(1 068 eyes)underwent cataract surgeries. Among the 1 068 eyes, signs of IFIS were noted in 34 eyes. Strong positive correlations were showed between finasteride(6.4%, OR=5.885), tamsulosin(25%, OR=21.578), reserpine(16.7%, OR=12.947), clozapine(66.7%, OR=139.467), post-panretinal photocoagulation(14.3%, OR=10.789)and IFIS. Pupil size was inversely related to IFIS incidence(P<0.001). A dilated pupil smaller than 7.25mm could predict IFIS(P<0.001).

CONCLUSION: The incidence rate of IFIS was 3.18%. Reserpine, clozapine and post-panretinal photocoagulation emerged as new risk factors for IFIS. A small dilated pupil may imply IFIS occurrence.