Purpose: To evaluate the correlation between silodosin and Intraoperative Floppy Iris Syndrome (IFIS) and compare it with other a1-adrenergic receptor antagonists (a1-ARAs) and other factors predisposing to IFIS. Methods: From the cases who underwent phacoemulsi cation between 2014 and 2020, we identi ed all patients who, during their preoperative assessment, reported an a1-ARAs intake (exposed group). These patients were matched utilizing a propensity score matching analysis, with an otherwise homogenous group of patients (control group), based on demographics and systemic/ocular comorbidities.Results: 350 patients were included in each group. In the exposed group, 177 (50.6%) patients were exposed to tamsulosin, 105 (30%) to alfuzosin, 43 (12.2%) to silodosin. Regarding IFIS, it was observed in 21.5% of patients on tamsulosin (38/177), 11.4% on alfuzosin (12/105), 37.2% on silodosin (16/43), and 3.4% in the controlled group (12/350). In a multiple regression model analysis, the only two factors that were signi cantly associated with IFIS development were silodosin and tamsulosin yielding an adjusted odds ratio of 8.471 (95%CI: 4.005-17.920), and 3.803 (95%CI: 2.231-6.485), respectively.Conclusion: Silodosin has been demonstrated as a predisposing factor, strongly correlated with IFIS development. These results should increase awareness to cataract surgeons, to carefully assess their patients preoperatively for exposure to silodosin, and employ the appropriate prophylactic measures to ameliorate the impact of silodosin intake on the surgical outcome. Key MessagesWhat is known: a1-adrenergic receptor antagonists (a1-ARAs), and especially tamsulosin, are considered to be the main predisposing factors for the development of Intraoperative Floppy Iris Syndrome (IFIS). However, there is very limited data regarding the correlation between the intake of silodosin, a newest uroselective a1-ARA, and IFIS New information:In an observational cohort study with propensity score-matching, silodosin, demonstrated strong correlation to IFIS development and should be classi ed among the main risk factors for the appearance of oppy iris.Silodosin intake seems to have a higher odds ratio than any other factor predisposing to IFIS, and therefore, it should be included in the preoperative assessment of cataract surgery in order to minimize the detrimental effects of IFIS by employing the appropriate prophylactic measures.

Purpose: To evaluate the correlation between silodosin and Intraoperative Floppy Iris Syndrome (IFIS) and compare it with other a1- adrenergic receptor antagonists (a1-ARAs) and other factors predisposing to IFIS.Methods: From the cases who underwent phacoemulsification between 2014 and 2020, we identified all patients who, during their preoperative assessment, reported an a1-ARAs intake (exposed group). These patients were matched utilizing a propensity score matching analysis, with an otherwise homogenous group of patients (control group), based on demographics and systemic/ocular comorbidities.Results: 350 patients were included in each group. In the exposed group, 177 (50.6%) patients were exposed to tamsulosin, 105 (30%) to alfuzosin, 43 (12.2%) to silodosin. Regarding IFIS, it was observed in 21.5% of patients on tamsulosin (38/177), 11.4% on alfuzosin (12/105), 37.2% on silodosin (16/43), and 3.4% in the controlled group (12/350). In a multiple regression model analysis, the only two factors that were significantly associated with IFIS development were silodosin and tamsulosin yielding an adjusted odds ratio of 8.471 (95%CI: 4.005-17.920), and 3.803 (95%CI: 2.231-6.485), respectively.Conclusion: Silodosin has been demonstrated as a predisposing factor, strongly correlated with IFIS development. These results should increase awareness to cataract surgeons, to carefully assess their patients preoperatively for exposure to silodosin, and employ the appropriate prophylactic measures to ameliorate the impact of silodosin intake on the surgical outcome.