EN ISO 11979-2:1999
(Main)Ophthalmic implants - Intraocular lenses - Part 2: Optical properties and test methods (ISO 11979-2:1999)
Ophthalmic implants - Intraocular lenses - Part 2: Optical properties and test methods (ISO 11979-2:1999)
Ophtalmische Implantate - Intraokularlinsen - Teil 2: Optische Eigenschaften und Prüfverfahren (ISO 11979-2:1999)
Dieser Teil von ISO 11979 legt Anforderungen und Prüfverfahren für bestimmte optische Eigenschaften von Intraokularlinsen (IOLs) fest. Er gilt für nicht-torische, monofokale Intraokularlinsen zur Implantation in die vorderen Abschnitte des menschlichen Auges, ist jedoch nicht auf die Anwendung bei diesen Typen von Intraokularlinsen beschränkt. Er gilt nicht für Hornhautimplantate.
Implants ophtalmiques - Lentilles intraoculaires - Partie 2: Propriétés optiques et méthodes d'essai (ISO 11979-2:1999)
La présente partie de l'ISO 11979 définit les exigences et les méthodes d'essai relatives à certaines propriétés optiques des lentilles intraoculaires (LIO).Elle est applicable, mais non limitée, aux lentilles intraoculaires non toriques, monofocales, destinées à être implantées dans le segment antérieur de l'oeil humain, et exclut les implants cornéens.
Očesni vsadki (implantati) - Intraokularne leče - 2. del: Optične lastnosti in preskusne metode (ISO 11979-2:1999)
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2000
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Ophthalmic implants - Intraocular lenses - Part 2: Optical properties and test methods
(ISO 11979-2:1999)
Ophtalmische Implantate - Intraokularlinsen - Teil 2: Optische Eigenschaften und
Prüfverfahren (ISO 11979-2:1999)
Implants ophtalmiques - Lentilles intraoculaires - Partie 2: Propriétés optiques et
méthodes d'essai (ISO 11979-2:1999)
Ta slovenski standard je istoveten z: EN ISO 11979-2:1999
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 11979-2
First edition
1999-12-15
Ophthalmic implants — Intraocular
lenses —
Part 2:
Optical properties and test methods
Implants ophtalmiques — Lentilles intraoculaires —
Partie 2: Propriétés optiques et méthodes d'essai
Reference number
ISO 11979-2:1999(E)
©
ISO 1999
ISO 11979-2:1999(E)
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ii © ISO 1999 – All rights reserved
ISO 11979-2:1999(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Requirements.2
4.1 General.2
4.2 Dioptric power.2
4.3 Imaging quality.2
4.4 Spectral transmittance .3
Annex A (normative) Measurement of dioptric power .4
Annex B (normative) Measurement of resolution efficiency .10
Annex C (normative) Measurement of MTF.12
Annex D (informative) Precision of dioptric power determination.16
Annex E (informative) Precision of imaging quality determination .17
Annex F (informative) Verification of ray trace calculations.18
Annex G (informative) Selected definitions.19
Bibliography.20
© ISO 1999 – All rights reserved iii
ISO 11979-2:1999(E)
Foreword
ISO (the International Organization for Standardization) 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 right 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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 11979 may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 11979-2 was prepared by Technical Committee ISO/TC 172, Optics and optical
instruments, Subcommittee SC 7, Ophthalmic optics and instruments.
ISO 11979 consists of the following parts, under the general title Ophthalmic implants — Intraocular lenses:
� Part 1: Vocabulary
� Part 2: Optical properties and test methods
� Part 3: Mechanical properties and test methods
� Part 4: Labelling and information
� Part 5: Biocompatibility
� Part 6: Shelf-life and transport stability
� Part 7: Clinical investigations
� Part 8: Fundamental requirements
Annexes A, B and C form a normative part of this part of ISO 11979. Annexes D, E, F and G are for information
only.
iv © ISO 1999 – All rights reserved
ISO 11979-2:1999(E)
Introduction
This part of ISO 11979 contains several test methods for which associated requirements are given and one test
method for which no requirement is formulated. The former are directly connected to the optical functions of
intraocular lenses. The latter, the test for spectral transmittance, has been provided for those interested in
information about UV transmission and in specific situations, e.g. when using laser light sources for medical
diagnosis and treatment.
Extensive interlaboratory testing has been carried out before setting the limits specified. Some basic problems were
encountered.
The accuracy in the determination of dioptric power has an error that is not negligible in relation to the half-dioptre
steps in which intraocular lenses are commonly labelled. The dioptric power tolerances take this fact into account.
Hence the limits set may lead to some overlap into the next labelled power, especially for high dioptre lenses.
Reference [1] gives further discussion on this subject.
The majority of lenses hitherto implanted have been made from poly(methyl methacrylate) (PMMA), and were
qualified using the method described in annex B. Thus the general clinical experience is associated with this level.
The method in annex B is limited in its applicability, however. The limits for the more general method in annex C
have been set in terms of MTF in an eye model, following two approaches. The first is by correlation to the method
and limit in annex B. Further discussion can be found in reference [2]. The second is set as a percentage of what is
calculated as theoretical maximum for the design, with the rationale that a minimum level of manufacturing
accuracy be guaranteed. For common PMMA lenses, these two limits correspond well with each other. For lenses
made of materials with lower refractive index, or with certain shape factors, or for extreme power lenses in general,
the latter limit is lower than the former. However, such lenses are already in use, indicating clinical acceptance. The
question arises which is the absolute lowest limit that is compatible with good vision. No definite answer can be
found, but following clinical data presented to the working group, an absolute lower limit has been set for the
calculation method.
NOTE It always was and still is the intention of the Technical Committees ISO/TC 172/SC 7 and CEN/TC 170 to prepare
identical ISO and CEN (European Committee for Standardization) standards on intraocular lenses. However, during the
preparation of part 7 of this series, problems were encountered with normative references to the existing ISO 14155 and EN 540
horizontal standards on clinical investigation of medical devices, which are similar but not identical.
ISO and CEN principles concerning normative references made it impossible to continue the preparation of identical
International and European Standards on the clinical investigation of intraocular lenses. As a result, two different standards
series have had to be prepared. For this part of ISO 11979, identical versions exist for ISO and CEN (ISO 11979-2 and
EN ISO 11979-2). For those parts where no identical versions exist, it is the intention of ISO/TC 172/SC 7 and CEN/TC 170 to
revise these standards with the goal to end up with identical ones as soon as identical ISO and CEN horizontal standards on
clinical investigations become available.
© ISO 1999 – All rights reserved v
INTERNATIONAL STANDARD ISO 11979-2:1999(E)
Ophthalmic implants — Intraocular lenses —
Part 2:
Optical properties and test methods
1 Scope
This part of ISO 11979 specifies requirements and test methods for certain optical properties of intraocular lenses
(IOLs).
It is applicable but not limited to non-toric, monofocal intraocular lenses intended for implantation into the anterior
segment of the human eye, excluding corneal implants.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 11979. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 11979 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
1�
ISO 6328: — , Photography — Photographic materials — Determination of ISO resolving power.
ISO 9334:1995, Optics and optical instruments — Optical transfer function — Definitions and mathematical
relationships.
ISO 9335:1995, Optics and optical instruments — Optical transfer function — Principles and procedures of
measurement.
ISO 11979-1:1999, Ophthalmic implants — Intraocular lenses — Part 1: Vocabulary.
U.S. Mil Std 150-A-1961, Photographic lenses.
3 Terms and definitions
For the purposes of this part of ISO 11979, the terms and definitions given in ISO 9334 and ISO 11979-1 apply.
NOTE Some definitions from ISO 11979-1 are reproduced for information in annex G.
1) To be published. (Revision of ISO 6328:1982)
© ISO 1999 – All rights reserved 1
ISO 11979-2:1999(E)
4 Requirements
4.1 General
All requirements stated below shall apply to the finished product as marketed. If applicable, the lens shall be
positioned as intended for use.
NOTE 1 The methods specified below are reference methods. Alternative methods demonstrated to produce results that are
equivalent to those obtained with the reference methods may also be used.
NOTE 2 Any validated procedures that ensure that IOLs are within the tolerances specified may be used in quality control.
4.2 Dioptric power
When determined by one of the methods described in annex A, the dioptric power as stated by the manufacturer
(e.g. on the label of the IOL) shall, in any meridian, be within the tolerance limits specified in Table 1.
NOTE Astigmatism is implicitly limited by the requirement that dioptric power be within the tolerance limits of Table 1 in all
meridians.
Table 1 — Tolerances on dioptric power
a
Tolerance on dioptric power
Nominal dioptric power range
D
D
0tou 15
� 0,3
� 15 tou 25 � 0,4
� 25 tou 30 � 0,5
� 30 � 1,0
a
The ranges apply to positive as well as to negative dioptric powers.
4.3 Imaging quality
Imaging quality shall be determined either according to the method described in annex B or to the method
described in annex C.
NOTE The method of annex C is more general. It can be used e.g. for extreme dioptric powers and for materials which
swell in aqueous humour, for which cases the method of annex B is not suitab
...
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