Effect of Pupil Size on Uncorrected Visual Acuity in Pseudophakic Eyes With Astigmatism

PURPOSE: To study the effect of pupil size on the relationship between refractive astigmatism and uncorrected distance visual acuity (UDVA) and pseudoaccommodation in pseudophakic eyes. METHODS: Thirty-six eyes from 36 patients who underwent phacoemulsification and intraocular lens (IOL) implantation were included. All eyes were divided into two groups based on the presence of postoperative with-the-rule astigmatism or against-the-rule astigmatism. Uncorrected and corrected distance visual acuity (CDVA), refractive astigmatism, subjective accommodation amplitude, and pupil sizes under photopic and mesopic conditions were measured 1 month postoperatively. The effects of pupil size on the relationship between refractive astigmatism and UDVA were investigated. RESULTS: Against-the-rule astigmatism had a moderate but significant negative linear correlation with UDVA irrespective of the pupil size (R 2 =0.60, P <.01). A moderate but significant negative linear correlation was found when the pupil diameter exceeded 2.9 mm in eyes with with-the-rule astigmatism (R 2 =0.46, P =.04). Refractive astigmatism was not significantly correlated with pseudoaccommodation regardless of the pupil diameter in either group. CONCLUSIONS: The results of the current study suggest that pupil size may have an impact on postoperative UDVA in eyes having against the-rule astigmatism and in eyes with a large pupil diameter and with-the-rule astigmatism.