Effect of Angle Alpha on Visual Quality after Multifocal Intraocular Lens Implantation

Objective: To evaluate the visual quality of patients with different angle alpha sizes after a multifocal intraocular lens (MIOL) implantation. Methods: This was a prospective case series study. Fifty-six patients (74 eyes) who had phacoemulsification with MIOL implantation were enrolled in the study from December 2016 to October 2018. The patients were divided into 3 groups based on the size of the preoperative angle alpha. There were 12 eyes in group A (0 mm 0.4 mm). 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 incidence of glare, and halo. The data were analyzed with an independent χ2 test or a ANOVA test. Results: The incidence of halo and glare in groups B and C was higher than that in group A (χ2=38.372, P=0.01). There were no significant differences in the far, intermediate, or near vision between the three groups (P>0.05). Angle alpha had no significant effect on the MTF, night hyperopia, double vision, mixed focus or starburst (P>0.05). Conclusions: When angle alpha is greater than 0.4 mm, the incidence of glare and halo increases. In clinical work, for patients with a larger angle alpha, the choice to implant MIOLs should be carefully evaluated. Key words: phacoemulsification for cataract; multifocal intraocular lens; angle alpha; modulation transfer function