What tool is typically used to measure pupillary distance?

The tool that is typically used to measure pupillary distance is the pupillometer. This instrument is specifically designed for the purpose of accurately determining the distance between the center of one pupil to the center of the other, which is crucial for ensuring proper lens placement in eyewear.

Pupillary distance is an important measurement, as it helps opticians and eye care professionals align the optical centers of the lenses with the wearer's pupils, which can significantly affect visual comfort and clarity. The pupillometer provides precise measurements, often digitally, which enhances the accuracy compared to more manual methods.

While a caliper is often associated with measuring distances, it is more commonly used for measuring physical dimensions of objects rather than specific anatomical features like pupillary distance. An optometer is primarily utilized to measure refractive errors in the eye, and an eyeglass fitting kit may contain various tools for fitting lenses and frames but does not specifically measure pupillary distance. Thus, the pupillometer stands out as the most suitable and effective tool for this specific task.