Purpose: To evaluate the influence of pupil dynamics on the defocus profile and area-of-focus of eyes implanted with a diffractive multifocal intraocular lens (IOL).
Methods: This prospective randomized trial was conducted at the Department of Ophthalmology, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil. Thirty-eight patients were randomly assigned to receive the multifocal SN6AD1 (n=20) or the aspheric monofocal SN60WF (aIOL) (n=18) IOLs bilaterally. Dynamic pupillometry, visual acuity for distance and near, corrected and uncorrected, and a defocus profile were assessed postoperatively. The area-of-focus was calculated using an empirical polynomial model of the defocus profile.
Results: Sixteen patients (32 eyes) in the multifocal SN6AD1 group and 17 patients (34 eyes) in the aspheric monofocal SN60WF group completed the 1-year follow-up. There were no significant between-group differences in monocular uncorrected distance or near visual acuity. The defocus profiles of the mfIOL group showed a double peak, whereas those of the aspheric monofocal SN60WF group showed only one peak, which is typical for a monofocal intraocular lens. The area-of-focus of the aIOL group (4.66 ± 1.51 logMARxD) was significantly different from that of the multifocal SN6AD1 (1.99 ± 1.31 logMARxD). Pupil size at maximum contraction after exposure to a flash of 30 cd/m2 for 1 second was significantly correlated with a better area-of-focus in the multifocal SN6AD1 group (r=0.54; p=0.0017), whereas this was not the case in the aspheric monofocal SN60WF group.
Conclusion: These findings indicate that in eyes implanted with an multifocal SN6AD1, the smaller the pupil size, the better is the area-of-focus and hence the better is the visual performance. This correlation was not found for the aspheric monofocal SN60WF.