“Where there is light, there are reflections”—this also applies to the slit lamp examination. As a rule, we decide to ignore such mirror phenomena. Often these Purkinje reflections are also perceived as disturbing, especially in image documentation, where they—unfiltered—can destroy the aesthetics of an image. One might also argue that ophthalmology has developed so far diagnostically with a great variety of methods that the observation of reflecting phenomena with the slit lamp is outdated. However, the fact remains that every practicing ophthalmologist spends many hours at the slit lamp, and that it makes sense to learn to interpret the information contained in the Purkinje images: This primarily concerns the curvature and geometric alignment of the refracting surfaces of IOLs as well as contact lenses and the corneal surface after refractive procedures.