Precision dynamic pupillometry is now a fundamental part of qualification, screening and planning in refractive surgery. Due to iris vibrations and various noises, measuring pupil diameter is more complicated than it might seem. The pupil is never at rest, it performs continuous oscillations with an amplitude of +/- 0.5mm, so an attempt to measure the pupil diameter relying on a single scan is not sufficient to estimate the true average value of the pupil diameter – the examiner may capture the image of the pupil at the minimum, or maximum.