ISO/TR 11797:2024

Ophthalmic optics – Spectacle lenses – Power and prism measurements

This document describes the methods currently used in applying tolerances to the focal powers of spectacle lenses and methods that can be considered for adoption in the future; it also describes methods of measuring the prism imbalance (relative prism error) between the lenses of a mounted pair. The results of a 2014 survey of manufacturing capability for lens power and a 2018 international web survey are discussed, as are possible new methods for applying tolerances to the focal power of spectacle lenses.