1、Ophthalmic optics Contact lensesPart 4: Physicochemical properties of contact lens materials (ISO 18369-4:2017)BS EN ISO 18369-4:2017BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National forewordThis British Standard is the UK implementation of EN ISO 18369-4:2017
2、. It is identical to ISO 18369-4:2017. It supersedes BS EN ISO 18369-4:2006, which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee CH/172/9, Contact lenses and contact lens care products.A list of organizations represented on this committee can be obtained o
3、n request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017 Published by BSI Standards Limited 2017ISBN 978 0 580 87560 1ICS 11.040.70Compliance with a Br
4、itish Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2017.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS EN ISO 18369-4:2017EUROPEAN STANDA
5、RDNORME EUROPENNEEUROPISCHE NORMEN ISO 18369-4September 2017ICS 11.040.70 Supersedes EN ISO 18369-4:2006EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGCEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2017 CEN Ref. No. EN ISO 18369-4:
6、2017: EAll rights of exploitation in any form and by any means reserved worldwide for CEN national MembersOphthalmic optics Contact lenses Part 4: Physicochemical properties of contact lens materials (ISO 18369-4:2017)Optique ophtalmique Lentilles de contact Partie 4: Proprits physicochimiques des m
7、atriaux des lentilles de contact (ISO 18369-4:2017)Augenoptik Kontaktlinsen Teil 4: Physikalisch-chemische Eigenschaften von Kontaktlinsenmaterialien (ISO 18369-4:2017)This European Standard was approved by CEN on 1 July 2017.CEN members are bound to comply with the CEN/CENELEC Internal Regulations
8、which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.This
9、European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.CEN members
10、 are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
11、 Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.English VersionEN ISO 18369-4:2017 (E)European forewordThis document (EN ISO 18369-4:2017) has been prepared by Technical Committee ISO/TC 172 “Optics and photonics” in collaboration with Technical Committee
12、CEN/TC 170 “Ophthalmic optics” the secretariat of which is held by DIN.This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2018, and conflicting national standards shall be withdrawn at the late
13、st by March 2018.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.This document supersedes EN ISO 18369-4:2017.According to the CEN-CENELEC Internal Re
14、gulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland,
15、 Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.2BS EN ISO 18369-4:2017ISO 18369-4:2017(E)Foreword iv1 Scope . 12 Normative references 13 Terms and definitions . 14 Phy
16、sicochemical properties of contact lenses . 14.1 Repeatability, test methods and units of measure . 14.2 Extractables . 24.2.1 General 24.2.2 Principle 24.2.3 Apparatus . 24.2.4 Reagents 34.2.5 Test samples. 44.2.6 Test procedure . 44.2.7 Calculation of results 44.2.8 Test report . 54.3 Rigid lens f
17、lexural deformation and rupture 54.3.1 Principle 54.3.2 Sampling 54.3.3 Preparation of samples 64.3.4 Apparatus . 64.3.5 Procedure . 84.3.6 Test result . 84.4 Oxygen permeability 94.4.1 General 94.4.2 Common elements of the methods 94.4.3 Polarographic method 104.4.4 Normalization of the corrected o
18、xygen permeability using reference lenses .184.4.5 Test report 194.5 Refractive index . 194.5.1 General. 194.5.2 Abbe refractometer 194.5.3 Test samples204.5.4 Procedure 204.5.5 Expression of test results 214.5.6 Test report 214.6 Water content 224.6.1 General. 224.6.2 Gravimetric determination of w
19、ater content/absorption by loss on drying using an oven .224.6.3 Test report 245 Test report 24Annex A (informative) Determination of oxygen permeability using the coulometric method 25Annex B (informative) Determination of water content by refractive index .32Annex C (informative) Calculation of ox
20、ygen permeability of hydrogel lenses based on water content 33Annex D (informative) Measurement of refractive index using a prism coupling device 34Bibliography .36 ISO 2017 All rights reserved iiiContents PageBS EN ISO 18369-4:2017ISO 18369-4:2017(E)ForewordISO (the International Organization for S
21、tandardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the ri
22、ght to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedure
23、s used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial ru
24、les of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights ident
25、ified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation o
26、n the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/forewo
27、rd.html.This document was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 7, Ophthalmic optics and instruments.This second edition cancels and replaces the first edition (ISO 18369-4:2006), which has been technically revised.A list of all parts in the ISO 18369 seri
28、es can be found on the ISO website.iv ISO 2017 All rights reservedBS EN ISO 18369-4:2017Ophthalmic optics Contact lenses Part 4: Physicochemical properties of contact lens materials (ISO 18369-4:2017)1 ScopeThis document specifies the methods of testing the physicochemical properties of contact lens
29、 materials. These are extraction, rigid lens flexure and breakage, oxygen permeability, refractive index and water content.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated re
30、ferences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 3696:1987, Water for analytical laboratory use Specification and test methodsISO 18369-1:2017, Ophthalmic optics Contact lenses Part 1: Vocabulary, c
31、lassification system and recommendations for labelling specificationsISO 18369-3:2017, Ophthalmic optics Contact lenses Part 3: Measurement methods3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 18369-1 apply.ISO and IEC maintain terminological databa
32、ses for use in standardization at the following addresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing platform: available at http:/www.iso.org/obp 4 Physicochemical properties of contact lenses4.1 Repeatability, test methods and units of measureThe physicochemical
33、 properties or conditions listed in Table 1 are measurable characteristics of hydrogel and non-hydrogel materials that have been used to produce commercially available contact lenses.Table 1 Physicochemical properties: Test methods and units of measureProperty Units of Test method RepeatabilityExtra
34、ctables mass % 4.2baDk is reported in units of 1011(cm2/s) ml O2/(ml mmHg) and called “Dk units” or barrer.bRepeatability of these test results shall be established in individual laboratories according to ISO 18369-1:2017, 3.1.12.8, 3.1.12.9, 3.1.12.9.1, 3.1.12.9.2 and 3.1.12.9.3.INTERNATIONAL STAND
35、ARD ISO 18369-4:2017(E) ISO 2017 All rights reserved 1BS EN ISO 18369-4:2017ISO 18369-4:2017(E)Property Units of Test method RepeatabilityFlexural deformation g 4.3bOxygen permeability Dk unitsa4.4 10 %Refractive index dimensionless 4.5 0,01Water content weight % 4.6 2 % absoluteaDk is reported in u
36、nits of 1011(cm2/s) ml O2/(ml mmHg) and called “Dk units” or barrer.bRepeatability of these test results shall be established in individual laboratories according to ISO 18369-1:2017, 3.1.12.8, 3.1.12.9, 3.1.12.9.1, 3.1.12.9.2 and 3.1.12.9.3.Clause 4 is applicable to testing laboratories, suppliers
37、and users of contact lens products or services in which measurement results are used to demonstrate compliance to specified requirements.Alternative test methods and equipment may be used provided the accuracy and precision are equivalent to or more capable than the test methods described.In develop
38、ing new test methods, these should be capable of measuring the various parameters with a precision (R4 ISO 2017 All rights reservedBS EN ISO 18369-4:2017ISO 18369-4:2017(E)m2is the mass of extracted lenses.Alternatively, the extraction solvent can be quantitatively dried down to constant mass and th
39、e resultant extractables residue weighed to the nearest 0,1 mg (m 3) and used to calculate the quantity of extracted material as shown in Formula (2):% extracted=mm31100 (2)4.2.8 Test reportThe test report for extractables shall conform to that in Clause 5 and contain the following information for h
40、ydrophilic material:a) the composition of the initial hydrating solution;b) a statement as to whether the percentage of extractable substances has been adjusted for the salt content of the hydrating solution;c) if the contact lenses were equilibrated in water before the beginning of the test;d) the
41、method used to calculate quantity of extracted material, e.g. whether Formula (1) or Formula (2) was used for the calculation.4.3 Rigid lens flexural deformation and rupture4.3.1 PrincipleThe test, which is a destructive test, applies an increasing load at the edge of a rigid lens across the total d
42、iameter until, ultimately, the test sample fractures. The test is carried out in an apparatus which allows the load and flexural deformation to be monitored continuously. Both the flexural deformation strength and flexural deformation at rupture are determined, as well as flexural deformation streng
43、th at 30 % deformation. The latter is derived from the flexural load-deformation curve. Either normal production or specially constructed rigid contact lenses can be tested.It should be noted that variability in the test results may also result from inconsistencies in lens manufacturing method and m
44、ay not necessarily be indicative of the material itself.4.3.2 Sampling4.3.2.1 General samplesIn order to demonstrate the degree of resistance to breakage by the material, general samples for testing shall be normal, commercially available rigid, single vision contact lenses and shall not have been s
45、pecially treated or adjusted.Contact lenses which have toroidal zones or truncations shall not be used.The specified label back vertex power (FL) shall be the same for all samples and shall be between +0,50 D and 0,50 D.The specified back optic zone radius (r 0), or radius of the vertex sphere, shal
46、l be the same for all samples and shall be between 7,75 mm and 7,85 mm. ISO 2017 All rights reserved 5BS EN ISO 18369-4:2017ISO 18369-4:2017(E)4.3.2.2 Samples for material comparisonWhen special samples are prepared in order to compare materials, the contact lenses shall have the following specifica
47、tions: front surface: single cut, radius of curvature 8,000 mm 0,025 mm; back surface: single cut, radius of curvature 7,800 mm 0,025 mm; total diameter: 9,5 mm 0,1 mm; centre thickness: 0,20 mm 0,01 mm; edge thickness: 0,24 mm 0,01 mm; edge form: rounded; maximum prismatic error: 0,5 cm/m.The metho
48、d of manufacture shall be stated in the test report.4.3.2.3 QuantityThree contact lenses from each of three different material lots (total of nine contact lenses) shall be tested where a claim is made regarding flexure or strength.4.3.3 Preparation of samplesSamples shall be stored in standard salin
49、e solution conforming to ISO 18369-3:2017, 4.9, for at least 48 h prior to testing. The temperature of this saline solution shall be 20 C to 25 C.4.3.4 Apparatus4.3.4.1 Testing machine (see Figure 2), applying a load to the sample at a fixed rate in either the horizontal or vertical plane and composed of the units described in 4.3.4.1 to 4.3.4.3.Sample holding jig (see Figure 3), applying the load to the edge of the sample.The sample is set at the centre of the upper and lower contact faces so that th
