ISO INTERNATIONAL STANDARD 18369-4 Second edition 2017-08 Ophthalmic optics Contact lenses Part 4: Physicochemical properties of contact lens materials Optique ophtalmique - Lentilles de contact - Partie 4: Propriétes physicochimiques des matériaux des lentilles decontact Reference number ISO 18369-4:2017(E) so International Organization for Standardization @ IS0 2017 ed without license from IHS IS0 18369-4:2017(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 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 Internatinair PrganizationforStandardization @ IS0 2017 - All rights reserved etworking permitted without license from IHS IS0 18369-4:2017(E) Contents Page Foreword ..iv 1 Scope 2 Normativereferences ..1 3 Terms and definitions 4 Physicochemical properties of contact lenses ..1 4.1 Repeatability, test methods and units of measure .1 4.2 Extractables .2 4.2.1 General 2 4.2.2 Principle. 4.2.3 Apparatus. 2 4.2.4 Reagents .3 4.2.5 Test samples. 4 4.2.6 Test procedure .4 4.2.7 Calculation of results 5 4.2.8 Test report .5 4.3 Rigid lens flexural deformation and rupture .5 4.3.1 Principle .5 4.3.2 Sampling .5 4.3.3 Preparation of samples 6 4.3.4 Apparatus. .6 4.3.5 Procedure. .8 4.3.6 Test result. .8 4.4 Oxygen permeability .9 4.4.1 General. .9 4.4.2 Common elements of the methods .9 4.4.3 Polarographic method. 10 4.4.4 Normalization of the corrected oxygen permeability using reference lenses .18 4.4.5 Test report. 19 4.5 Refractive index. 19 4.5.1 General. .19 4.5.2 Abbe refractometer .19 4.5.3 Testsamples 20 4.5.4 Procedure 20 4.5.5 Expression of test results 21 4.5.6 Test report. 21 4.6 Water content. 22 4.6.1 General .22 4.6.2 Gravimetric determination of water content/absorption by loss on drying usinganoven .22 4.6.3 Test report. ..24 5 Test report. .24 Annex A (informative) Determination of oxygen permeability using the coulometric method ...25. Annex B (informative) Determination of water content by refractive index .32 Annex C (informative) Calculation of oxygen permeability of hydrogel lenses based on watercontent .33 Annex D (informative) Measurement of refractive index using a prism coupling device .34 Bibliography .36 iii ed without license from IHS