Overall temple measurement is most often stated in:

The overall temple measurement of eyeglasses is most often stated in millimeters because this unit allows for precise measurements that are necessary in the field of ophthalmic dispensing. Eyeglass frame components, including the temples, are typically small and require detail that millimeters can provide rather than larger units like centimeters, decimeters, or meters.

Millimeters are particularly useful in ensuring accuracy in fitting eyewear, as even slight variations can affect comfort and functionality for the wearer. Given that the dimensions of eyeglass frames and their components are inherently small, millimeters serve as the standard unit of measurement in the industry.