Changes in pupil size induced by phacoemulsification and posterior chamber lens implantation: Consequences for multifocal lenses

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Purpose: Because the optical performance of eyes implanted with multifocal intraocular lenses will theoretically depend upon the size and position of the pupil relative to the near and distance zones of the lens, we designed a study to determine whether preoperative pupil size is useful in predicting the postoperative pupil size of patients having phacoemulsification with posterior chamber lens implantation.Setting: Cullen Eye Institute, Department of Ophthalmology, Baylor College of Medicine, Houston, Texas.Methods: We prospectively measured pupil sizes preoperatively and postoperatively in 71 consecutive patients who had phacoemulsification with posterior chamber lens implantation. Pupil sizes were photographed under five lighting and viewing conditions that simulated a range of normal functional situations.Results: The mean change in preoperative to postoperative pupil size was less than 0.5 mm in all five testing conditions. However, changes in pupil diameter of 1.0 mm or more were noted in approximately 10% of patients in each testing situation. Sex, iris color, and the presence or absence of intraoperative iris trauma were not predictive factors for determining which patients sustained large postoperative changes in pupil size.Conclusions: Preoperative pupil size does not predict postoperative size with sufficient consistency to ensure a good match between pupil diameter and the zone sizes of multizone multifocal intraocular lenses.