Full Description ADOPTED_FROM:EN ISO 18526-1:2020 This document specifies the reference test methods for determining the spherical, cylindrical, and prismatic refractive power properties of unmounted and mounted plano lenses (non-corrective lenses) for eye and face protectors. This document does not apply to any eye and face protection product requirement standards for which other test methods are specified. Other test methods can be used provided they have been shown to be equivalent and include uncertainties of measurement no greater than those required by the reference method.