ISO INTERNATIONAL STANDARD 21987 Second edition 2017-07 Ophthalmic optics Mounted spectacle lenses Optique ophtalmique - Verres ophtalmiques montés Reference number IS0 21987:2017(E) International Organization for Standardization @ IS0 2017 =ZHEJIANG INST OF STANDARDIZATION C1 5956617 vided by IHS under lic Not for Resale, 2017/9/27 05:18:2 itted without license from IHS IS0 21987:2017(E) COPYRIGHTPROTECTEDDOCUMENT IS0 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISOcopyrightoffice Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 [email protected] www.iso.org Intenationaibr PrganizationforStandardization icensee-ZHEJIANG INST.OF STANDARDIZRoISQ s1.7 - All rights reserved Not for Resale, 2017/9/27 05:18:24 etworking permitted without license from IHS IS0 21987:2017(E) Contents Page Foreword ..V 1 Scope .1 2 Normative references .1 3 Terms and definitions 4 Classification ..3 5 Requirements .3 5.1 Reference temperature .3 5.2 Lenses used in manufacturing complete spectacles .3 5.3 Optical requirements. .3 5.3.1 General. .3 5.3.2 Back vertex power 4 5.3.3 Direction of the cylinder axis .4 5.3.4 Additionpowerorvariationpower 5 5.3.5 Prism imbalance (relative prism error) for mounted single-vision lenses (excluding position-specific single-vision lenses) and multifocal lenses 5 5.3.6 Prism imbalance (relative prism error) for position-specific single-vision lensesandpower-variationlenses. .7 5.4 Requirements for thickness 1 5.5 Requirements for positioning ..8 5.5.1 Multifocal lenses. ..8 5.5.2 Position-specific single-vision lenses and power-variation lenses ..9 5.6 Orientation requirement for polarizing lenses .9 6 Verification methods .9 6.1 General .9 6.2 Verification method for back vertex power .9 6.3 Verification method for the direction of the cylinder axis.. .9 6.4 Verification method for addition power or variation power .10 6.4.1 General .10 6.4.2 Method forverification ofaddition power formultifocal lenses .10 6.4.3 Method for verification of variation power (including addition power) for power-variationlenses. ..10 6.5 Verification method for position and tilt. ..11 6.6 Verification method for prism imbalance (relative prism error) for mounted single-vision lenses (excluding position-specific single-vision ienses) and multifocal lenses .11 6.7 Verification method for planes of transmission of polarizing lenses. .11 6.7.1 General ..11 6.7.2 Apparatus. .11 6.7.3 Procedure .12 6.8 Inspection method for material and surface quality ..12 7 Marking for position-specific single-vision lenses and power-variation lenses ..12 7.1 Permanent marking ..12 7.2 Optional non-permanent marking ..13 8 Recommendations on mounting ..13 9 Identification ..13 10 Reference to this document ..13 Annex A (informative) Material and surface quality .14 Annex B (informative) Recommendations on mounting ..15 iii ZHEJIANG INST OF STANDARDIZATION C1 5956617 ed withoutlicense from IHS