1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationOphthalmic optics and instruments Instruments to measure axial distances in the eyeBS EN ISO 22665:2012National forewordThis British Standard is the UK implementation of EN ISO 2
2、2665:2012.The UK participation in its preparation was entrusted by Technical CommitteeCH/172, Ophthalmic optics, to Subcommittee CH/172/6, Ophthalmic instruments.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to inc
3、lude all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2013.Published by BSI Standards Limited 2013 ISBN 978 0 580 73937 8 ICS 11.040.70Compliance with a British Standard cannot confer immunity from legal obligations.This
4、 British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2013.Amendments issued since publicationDate Text affectedBRITISH STANDARDBS EN ISO 22665:2012EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 22665 December 2012 ICS 11.040.70 En
5、glish Version Ophthalmic optics and instruments - Instruments to measure axial distances in the eye (ISO 22665:2012) Optique et instruments ophtalmiques - Appareil pour le mesurage de la longueur axiale de loeil (ISO 22665:2012)Augenoptik und ophthalmische Instrumente - Instrumente zur Messung der A
6、chslnge des Auges (ISO 22665:2012)This European Standard was approved by CEN on 30 November 2012. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to
7、-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 European Standard exists in three official versions (English, French, German). A version in any other language made by translat
8、ion 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 are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland,
9、Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION CO
10、MIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 22665:2012: EBS EN ISO 22665:2012EN ISO 22665:2012 (E) 2 Cont
11、ents Page Foreword . 3 BS EN ISO 22665:2012EN ISO 22665:2012 (E) 3 Foreword This document (EN ISO 22665:2012) has been prepared by Technical Committee ISO/TC 172 “Optics and photonics“ in collaboration with Technical Committee CEN/TC 170 “Ophthalmic optics” the secretariat of which is held by DIN. T
12、his 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 June 2013, and conflicting national standards shall be withdrawn at the latest by June 2013. Attention is drawn to the possibility that some of the e
13、lements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this
14、 European Standard: 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, Romania, Slovakia
15、, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 22665:2012 has been approved by CEN as a EN ISO 22665:2012 without any modification. BS EN ISO 22665:2012ISO 22665:2012(E)IntroductionThe measurement of the axial length of the human eye is one
16、of the pre-requisites for the calculation of the necessary power of an artificial lens that is to be implanted in the eye during cataract and/or refractive surgery.Since the 1950s ultrasound biometry instruments have been used for ocular distance measurements. Depending on how the sound waves are co
17、upled into the eye, two different measurement methods are applied in ultrasound biometry: immersion and contact techniques. In recent years, optical biometry instruments based on partial coherence interferometry have established themselves as an alternative to echometry.Neither instrument is calibra
18、ted against a common standard. As a result, there are systematic differences between measurements taken with different biometers. The resulting errors can affect surgical outcomes for patients.iv ISO 2012 All rights reservedBS EN ISO 22665:2012Ophthalmic optics and instruments Instruments to measure
19、 axial distances in the eye1 ScopeThis International Standard is applicable to instruments and methods used for measuring the axial length of the human eye.It defines minimum requirements for such instruments and systems and defines test methods and procedures to verify that a system or instrument q
20、ualifies as an axial length measuring device in accordance with this International Standard.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest editio
21、n of the referenced document (including any amendments) applies.IEC 60601-1, Medical electrical equipment Part 1: General requirements for basic safety and essential performance3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1axial lengthdistance
22、 along the axis of a human eye between the anterior corneal surface to either the inner limiting membrane (ILM) of the retina or the retinal pigment epithelium (RPE) of the retinaNOTE The separation between the ILM (anterior retina) and RPE (posterior retina) is approximately 100 m at the centre of
23、the fovea and 300 m immediately outside the fovea. Different methods exist to assess axial length, e.g. peak and rising edge detection of fundus echoes in ultrasound instruments (using ILM) or determination of the optical path length to the RPE in optical biometry.3.2aphakic modemeasurement mode and
24、/or instrument setting for an axial length measuring device which is to be used for the measurement of an aphakic eye (eye without lens)3.3contact ultrasoundcontact modecoupling technique in echo biometry by which the measuring transducer probe is in direct contact with the cornea3.4echo biometrymet
25、hod to determine the axial length of a human eye by measuring the time of flight of an ultrasound pulse between two echo-generating structures in the eye3.5group refractive indexratio c0/cgbetween the speed of light in vacuum (c0) and the group velocity of light propagation (cg) through a medium or
26、a biological tissueINTERNATIONAL STANDARD ISO 22665:2012(E) ISO 2012 All rights reserved 1BS EN ISO 22665:2012ISO 22665:2012(E)3.6immersion ultrasoundimmersion modecoupling technique in echo biometry by which the measuring transducer probe is separated from the cornea by a water or liquid standoff3.
27、7optical biometryoptical method to measure the axial length of a human eye3.8phakic modemeasurement mode and/or instrument setting for an axial length measuring device which is to be used for the measurement of a phakic eye (eye with a crystalline lens)3.9acoustical impedanceZ material property defi
28、ned as the product of the velocity of sound in that material with its density:Z =where is the velocity of sound in the material; is the density of the material.4 RequirementsThe axial length measuring device shall conform to the requirements given below. Conformity shall be verified as described in
29、Clause 5.The radial and axial dimensions of three test bodies conforming to the requirements of Annex A shall be determined using the instrument under test and shall be compared to the true dimensions. All measured values shall lie within 100 m of the true dimensions.5 Test methods5.1 GeneralThe mea
30、surements aim at comparing axial and radial dimensions of the test cylinders.All test bodies shall be placed in a position relative to the measuring instrument or sensor (transducer) which is comparable to the patients eye position during clinical measurements. Axial measurements are to be performed
31、 along the cylinder axis, radial measurements along a diameter. In each orientation, 10 independent measurements shall be carried out and averaged to give the respective test cylinder dimension.To perform independent measurements it is necessary to adjust the measuring device anew for each new singl
32、e measurement.5.2 True parameters of the test bodiesThe true dimensions of the test bodies shall be determined using a mechanical calliper with an accuracy of at least or better than 10 m, preferably at the same temperature at which the measurements with the axial length measuring devices were perfo
33、rmed. Test results shall be evaluated according to the general rules of statistics.The group refractive index and the velocity of sound and their temperature dependences, as well as the acoustical impedance of the material, are to be specified.2 ISO 2012 All rights reservedBS EN ISO 22665:2012ISO 22
34、665:2012(E)5.3 Measurements with ultrasound biometry instrumentsMeasurements using ultrasound instruments shall be performed in contact mode as well as in immersion mode. For immersion measurements, the test cylinders are to be immersed in distilled water in a suitable cuvette and oriented according
35、 to the desired dimension to be measured.To prevent excessive uptake of water, the test bodies shall only be immersed in water for the duration of the measurements.The ultrasound instrument has to be set up to operate in the aphakic mode.The temperature of the test bodies shall be determined in orde
36、r to allow a temperature correction for the propagation speed of sound through the test body material.The measured values are transformed into times of flight and then reconverted into geometrical distances by means of the temperature-corrected velocity of sound for the test body material. For detai
37、ls, see Annex A.5.4 Measurements with optical biometry instrumentsThe optical biometry instrument has to be set up to operate in a mode which allows the optical path length of the test body to be obtained.The temperature of the test bodies shall be determined in order to allow a temperature correcti
38、on for the group refractive index of the test body material.The measured values are then reconverted into geometrical distances by means of the temperature-corrected group refractive index for the test body material. For details, see Annex A.6 Accompanying documentsThe instrument shall be accompanie
39、d by documents containing instructions for use and any necessary precautions. In particular, these documents shall contain the following information:a) name and address of the manufacturer or his authorized representative as required by legislation;b) instructions as to effective disinfection of the
40、 components of the axial length measuring device which are in contact with the patient with particular reference to instruments returned to the manufacturer for repair and maintenance;c) any additional documents as specified in IEC 60601-1;d) a reference to this International Standard, i.e. ISO 2266
41、5:2012, if the manufacturer or supplier claims compliance with it;e) instructions for use, if not already specified by IEC 60601-1.7 MarkingThe instrument shall be permanently marked with at least the following information:a) name and address of manufacturer or supplier;b) name, model, serial number
42、;c) additional marking as required by IEC 60601-1. ISO 2012 All rights reserved 3BS EN ISO 22665:2012ISO 22665:2012(E)Annex A (normative) Test bodies and evaluation of measurementsA.1 Test bodiesA.1.1 GeneralThe test bodies are cylinders made of a suitable material that represent the distances of sm
43、all, medium and long eyes; they shall be manufactured with a tolerance 0,01 mm.PMMA has been used in a variety of ultrasound applications as an echo-generating material; millions of PMMA lenses have been implanted in human eyes, the axial length of which is measured by ultrasound. Therefore, A.1.2 g
44、ives the specification of a test body on the basis of the relevant material parameters for test bodies made from PMMA.Other suitable materials may be used and will be necessary, e. g. for ultrasound biometry instruments that may not be sensitive enough to display echoes with a long travel time throu
45、gh PMMA.When selecting an appropriate material, it is recommended to consider the materials acoustical impedance to cause changes similar to those at the tissue margins to be detected in the human eye.NOTE 1 Otherwise, the detection mechanism will be different from that of the human eye, thereby cau
46、sing a non-negligible impact on the measured axial lengths.NOTE 2 Consideration may be given to selecting a combination of more than one material.If a material other than PMMA is to be used, the specification of the test body and evaluation of results shall follow along the lines of the approach wit
47、h PMMA, but with the appropriate parameters of the selected material and the calculations made based on them.A.1.2 Material propertiesThe following material properties are used for the measurement evaluation:T temperature of the test body (in C);c(T) temperature-dependent velocity of sound at workin
48、g frequency for the test body material (in m/s);ng(T) temperature-dependent group refractive index at laser wavelength for the test body material.For PMMA:The temperature-dependence of the ultrasound velocity is assumed to be the same as given by Asay et al1for 6 MHz:cT TT() ,(),()= 275192647 25 8 6
49、31 10 2532(A.1)The temperature-dependence of the group refractive index is assumed to be the same as the respective relation for the phase refractive index2and can be expressed as:nT nTTg() ()=050810 (A.2)with n0= 1,498 at T0= 20 C3.4 ISO 2012 All rights reservedBS EN ISO 22665:2012ISO 22665:2012(E)For materials other than PMMA, the relations given in Equations (A.1) and (A.2) will need to be replaced with the respective relations for the selected material.A.1.3 Geometry of test cylindersThe lengths l of the te
