Role of angle κ in visual quality in patients with a trifocal diffractive intraocular lens

Purpose: To evaluate the visual quality of patients with different angle kappa sizes after a trifocal diffractive intraocular lens (IOL) implantation. Setting: The Affiliated Hospital of Qingdao University, Qingdao, China. Design: Prospective case series. Methods: Patients who had phacoemulsification with the implantation of the trifocal IOL AT LISA tri 839MP were enrolled in the study. The patients were divided into 3 groups based on the size of the preoperative angle kappa. Monocular far, intermediate, and near uncorrected visual acuities were measured during a 3-month follow-up. Other outcome measurements taken were the modulation transfer function (MTF) cutoff, the Strehl ratio, and objective scatter index. All the patients completed a subjective questionnaire survey. Results: The study comprised 89 patients (89 eyes). The 3 groups showed statistically significant differences in the incidence of glare and halo after their surgery. There were no significant differences in the following variables: uncorrected far, intermediate, and near visual acuities, MTF cutoff, Strehl ratio, and spectacle independence. There was a significant difference in the MTF cutoff and Strehl ratio between the patients with the largest and the smallest angle kappa . Conclusions: The patients' postoperative far, intermediate, and near vision was not affected by their angle kappa . However, when angle kappa was greater than 0.4 mm, the incidence of glare and halo increased and when it was greater than 0.5 mm, patients' visual quality decreased. In clinical work, for patients with a larger angle kappa , the choice to implant a trifocal IOL should be carefully evaluated.