What type of error occurs when a lens is centered incorrectly over the pupillary axis?

When a lens is centered incorrectly over the pupillary axis, it typically results in a prismatic error. Prismatic error occurs when the optical center of the lens does not align properly with the pupil. This misalignment can cause light rays passing through the lens to deviate, resulting in unwanted prism effect and potentially leading to visual discomfort or distortion for the wearer. The significance of proper lens positioning over the pupillary axis cannot be overstated, as it directly impacts how effectively the lens corrects vision and how comfortable it feels to the wearer.

In contrast, optical errors generally refer to issues related to the lens prescription affecting visual clarity, cosmetic errors relate to how the glasses appear aesthetically, and postural errors involve the alignment of the glasses with the wearer's head position rather than their alignment with the eyes. Each of these errors could affect the overall experience of wearing glasses but does not specifically describe the consequence of misalignment with the pupillary axis as clearly as prismatic error does.