Influence of angle kappa on visual and refractive outcomes after implantation of a diffractive trifocal intraocular lens

Purpose: To evaluate changes in angle kappa following the implantation of a trifocal intraocular lens (IOL), and to assess the postoperative outcomes of patients with different angle kappa values. Setting: IOA Madrid Innova Ocular, Madrid, Spain Design: Prospective trial Methods: Sixty-three patients due to have bilateral implantation of the diffractive trifocal IOL (POD F, PhysIOL, Belgium) were included. Pupil offset was used as the best estimate of angle kappa and was measured using Pentacam (Oculus, Wetzlar, Germany) preoperatively and at 3-months after surgery. Postoperative refractive outcomes (sphere, cylinder, and MRSE) and visual outcomes at far, intermediate and near distance were assessed and compared between eyes with small pupil offset and eyes with large pupil offset. Quality of vision was assessed using a subjective questionnaire. Results: There was significant decrease in pupil offset post-operatively (mean: 0.197 ± 0.12 mm) compared to preoperatively (mean: 0.239 ± 0.12 mm), with a mean decrease of -0.042 mm (P = 0.0002). The same significant decrease was found for both the right eyes and left eyes, when analysed separately. No statistically significant difference was found in any of the refractive and visual acuity outcomes between eyes with small pupil offset and eyes with large pupil offset. The majority of patients (14 out of 16) complaining of significant halos had eyes with small pupil offset. Conclusion: Large pupil offset did not negatively affect visual and refractive outcomes. The tolerance to larger pupil offset might be due to the IOL optical design, with the first diffractive ring being larger than other commonly used multifocal IOLs. More studies comparing various diffractive IOL models will be useful to confirm such hypothesis.