Misalignment of flexible iris hook retractors for small pupil cataract surgery: effects on pupil circumference

A graphical method was used to assess the effect on pupil shape and circumference of various flexible iris hook malpositions. Results confirmed that all hook malpositions necessitate increased pupil stretching to create space to perform a capsulorhexis of a given diameter. This method also confirmed that the addition of a fifth hook to create a pentagonal pupil reduces pupil stretching by 17%. A simple method of marking the limbus before hook insertion to ensure equidistant hook separation and thus minimize pupil stretching is suggested.