Although originally the main goal of a cataract treatment was to eliminate scattering, IOLs have evolved enormously, first to additionally correct for refractive errors, but more recently, to compensate for high order aberrations (HOA), particularly spherical aberration. Also, new IOL designs aim at correcting presbyopia, either by expanding the depth-of-focus of the eye (multifocal IOLs—M-IOLs) or by dynamic changes of refractive power (accommodating IOLs—A-IOLs). With the increased sophistication of IOL designs, the impact of the IOL position becomes more critical. The aimed correction of corneal HOA by aspheric IOLs may be compromised by the induction of other HOA by a tilted/decentered lens.2 The performance of refractive M-IOLs (generally with concentric or segmented near/far regions) is critically affected by potential misalignments of the IOL.3 Finally, tilts and decentrations occurring with the only U.S. Food and Drug Administration (FDA)-approved A-IOL may also play a role in its function.4 Measurement of tilt and decentration of IOLs in pseudophakic eyes is therefore important as an endpoint for treatment, particularly with premium IOLs. On the other hand, in combination with biometrical and anatomical ocular data, knowledge of IOL and eye alignment is important in the development of customized computer eye models, which give insights into the relative contribution of different factors to optical performance with IOLs (Refs. 5 and 6). Several methods have been presented to measure IOL tilt and decentration. Purkinje imaging relies on the acquisition of pupillary images containing the image formed by the reflexes of the anterior cornea and anterior and posterior lens (Purkinje images I, III, and IV). The relative positions of PI, PIII, and PIV with respect to the pupil center are proportional to the eye rotation, IOL tilt, and IOL decentration.7,8 Purkinje imaging has been used successfully for lens phakometry,6,9–11 and for measurements of tilt and decentration of the natural lens,12,13 and IOLs (Refs. 1 and 14–1516). The device is simple and the measurement typically robust, although it may be subject to some limitations: difficulties in the association of the images to the corresponding reflecting surfaces [some authors have solved this by projecting a semicircular ring of light-emitting diodes (LEDs) yielding relative inverted images for PI and PIV (17)]; overlapping of the different Purkinje images (usually overcome by eccentric illumination and image acquisitions at different eccentric fixations);9 and requirement of ocular geometrical and biometrical information (normally obtained from the other instruments).