IS 18577 : 2024/ISO/TR 21958 : 2019 Ophthalmic Optics - Review of the Test Methods Used to Assess Scratch and Abrasion Resistance of Spectacle Lenses

NATIONAL FOREWORD

This Indian Standard which is identical to ISO/TR 21958 : 2019 'Ophthalmic optics - Review of the test methods used to assess scratch and abrasion resistance of spectacle lenses' issued by the International Organization for Standardization (ISO) was adopted by Bureau of Indian Standards on the recommendation of the Ophthalmic Instruments and Appliances Sectional Committee and after approval of the Medical Equipment and Hospital Planning Division Council

The text of ISO standard has been approved as suitable for publication as an Indian Standard without deviations. Certain conventions are however not identical to those used in Indian Standards. Attention is particularly drawn to the following:

a) Wherever the words 'International Standard' appear referring to this standard, they should be read as 'Indian Standard'; and

b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker.