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 κ 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 κ. 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 κ.

Conclusions: The patients' postoperative far, intermediate, and near vision was not affected by their angle κ. However, when angle κ 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 κ, the choice to implant a trifocal IOL should be carefully evaluated.