In recent years,there are many studies have reported that a small pupil syndrome appeared during routine phacoemulsification in patients with current or previous use of alpha-1 adrenergic receptor antagonists,with these clinical manifestations:an iris that appears floppy as it billows during normal irrigation and aspiration in the anterior chamber,a tendency for the iris to prolapse and progressive intraoperative miosis during surgery,which called intraoperative floppy iris syndrome This article mainly reviews the mobidity,pathogenesis,clinical features,complications,prophylaxis and treatment of the intraoperative floppy iris syndrome.