Influence of angle kappa and angle alpha on visual quality after implantation of multifocal intraocular lenses

Abstract

To assess the influence of angle kappa (κ) and angle alpha (α) on visual quality after multifocal intraocular lens (IOL) implantation. Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China. Prospective case series. Patients with cataract had phacoemulsification with TECNIS Symfony IOL implantation. The preoperative angle κ and angle α were measured using the iTrace device. Distance, intermediate, and near visual acuities were recorded 3months postoperatively. The Optical Quality Analyzing System was used to measure the objective scatter index (OSI), modulation transfer function (MTF) cutoff frequency, and Strehl ratio. A patient questionnaire was also administered. The study comprised 29 patients (57 eyes). Monocularly, the mean postoperative logarithm of the minimum angle of resolution (logMAR) uncorrected distance, intermediate, and near visual acuities were 0.03±0.09 (SD), 0.05±0.11, and 0.11±0.09, respectively. The mean postoperative logMAR corrected distance, distance-corrected intermediate, and distance-corrected near visual acuities were -0.01±0.05, 0.04±0.09, and 0.11±0.08, respectively. The mean OSI, MTF cutoff, and Strehl ratio were 1.27±0.84, 32.03±10.80 cycles per degree, and 0.17±0.05, respectively. The OSI (r=0.398, P=.005), MTF (r=-0.437, P=.002), and Strehl ratio (r=-0.419, P=.003) values were significantly correlated with angle κ. There was no correlation with angle α. Angle κ affected the objective visual quality multifocal after IOL implantation. The decision to implant a multifocal IOL should be carefully considered for patients with a large angle κ.