Intraoperative floppy iris syndrome (IFIS) is defined as an excessive billowing of the iris during cataract surgery. Floppy eyelid syndrome is defined as an excessive hyperlaxity of the eyelids. Based in our daily experience, we suspected FES to be associated with IFIS. This association has been investigated. The goal of the study was to explore whether FES was predictive of IFIS. We conducted a prospective observational single-center study at the University Hospital of Nice. IFIS and FES were investigated in patients undergoing cataract surgery from November 2019 to May 2021. In addition, tarsus and iris samples were harvested in 2 fresh cadavers, and Verhoeff staining was used to identify elastin fibers. We included 452 eyes (n=312 patients, 50.9% male) with a mean age of 71.7years (±11.4). IFIS was diagnosed in 88 (19.5%) patients, including 20 (4.4%) grade 1, 34 (7.5%) grade 2, and 33 (7.3%) grade 3. FES was diagnosed in 35 (7.7%) patients. PEX was found in 23 (5.1%) patients. On multivariate analysis, FES (P<0.001), pseudo exfoliation (P=0.017), intracameral dilatation (P<0.004), senior surgeons (P=0.009) and α1-ARA (P<0.001) were associated with IFIS. Elastin fibers were identified in small amounts in the tarsus samples but not in the iris samples. FES is predictive of IFIS. Surgeons should be aware of this association to prevent intraoperative complications.