For monofocal IOLs, a small amount of IOL decentration will have a minimal effect, particular in IOLs with low or zero spherical aberration. However, for extended depth of focus IOLs (Alcon Vivity, J&J Tecnis Symfony), bifocal IOLs (Alcon ReStor, J&J Tecnis Multifocal), or trifocal IOLs (Alcon PanOptix, J&J Synergy), achieving precise centration is important to deliver the best visual results.
We want to center the IOL in the pupil and the visual axis. This is why looking at the angle alpha and angle kappa at the pre-operative consultation is done. During surgery we can use the Purkinje images to help align the center of the IOL accurately. The patient can fixate on our microscope lights, particularly the lights that are co-axial to our oculars, and we can align the two commonly seen Purkinje images: the first and fourth. The first Purkinje image is a reflection from the anterior surface of the cornea while the fourth is from the posterior surface of the IOL.
Click to learn how I use Purkinje images to accurate center these IOLs: