Methods for quantifying pupil swim are disclosed in order to compensate for the same. A target image, in one embodiment, is displayed on a display of a head mounted display (HMD). Images of the target image are captured from a plurality of positions relative to an optical axis of an optics block of the HMD at an exit pupil of the HMD. The target image includes features and differences between observed locations of the features and their expected locations absent the optics block are determined. From these differences, a wavefront of the optics block is reconstructed and distortion corrections for the optics block are generated using the wavefront. The distortion corrections, when applied to a virtual scene, add pre-distortion that is canceled by the optical imperfections of the optics block as light of the virtual scene with the pre-distortion passes through the optics block.