Objective: The aim of this study was to investigate the role of pupillometry in predicting the occurrence of intraoperative floppy iris syndrome (IFIS) as a complication of cataract surgery, using the phacoemulsification technique in patients at the Department of Eye Diseases in University hospital of Split from February to June 2022. Subjects and methods: 72 patients between the ages of 60 and 85 who underwent cataract surgery at the Department of Ophthalmology at the University Hospital of Split in the specified five-month period were included. Data on the patient's age and sex, axial length of the eye, number of corneal endothelial cells, anterior chamber depth (ACD), keratometry, the existence of pseudoexfoliative syndrome (PEX), the therapy the patient is taking, and the incidence of IFIS were analyzed. Results: It was observed that patients with IFIS have a significantly smaller diameter of the pupil of the operated eye in the 5th second compared to subjects without IFIS (P=0.0411). The results also showed a connection between taking the α-adrenergic agonist tamsulosin and the occurrence of IFIS (P<0.001) due to the relaxation of the pupil dilator muscle, causing a significantly smaller diameter of the pupils of the operated eye in patients at 3400 ms (P=0.038) and 3800 ms (P=0.017). The presence of PEX syndrome in our study did not affect the occurrence of IFIS (P=0.348). Conclusion: A reduced diameter of the pupil of the eye indicates a high probability of developing a complication of cataract surgery known as floppy iris syndrome (IFIS). The use of tamsulosin therapy in patients who underwent cataract surgery using the phacoemulsification technique shows a significant risk for the development of IFIS. Applying the obtained results in practice would facilitate and enable a better preparation of the operator when performing the operation and a better assessment of the need to use drug therapy in the preparation of cataract operations.