EN ISO 19980:2005
(Main)Ophthalmic instruments - Corneal topographers (ISO 19980:2005)
Ophthalmic instruments - Corneal topographers (ISO 19980:2005)
ISO 19980:2005 is applicable to instruments, systems and methods that are intended to measure the surface shape of the cornea of the human eye.
It is not applicable to ophthalmic instruments classified as ophthalmometers.
ISO 19980:2005 defines certain terms that are specific to the characterization of the corneal shape so that they may be standardized throughout the field of vision care and have common meaning for all those who have occasion to participate in this area.
ISO 19980:2005 specifies minimum requirements for instruments and systems that fall into the class of corneal topographers. It specifies tests and procedures that will verify that a system or instrument complies with the standard and so qualifies as a corneal topographer in the meaning of this International Standard. It specifies certain tests and procedures that will allow the verification of capabilities of systems that are beyond the minimum required for corneal topographers.
Ophthalmische Instrumente - Hornhauttopographen (ISO 19980:2005)
Diese Internationale Norm gilt für Instrumente, Systeme und Methoden, deren Zweck in der Vermessung der Oberflächenform der Hornhaut eines menschlichen Auges liegt.
ANMERKUNG Diese Messungen sind Messungen der Oberflächenkrümmung in bestimmten Bereichen, dreidimensionale topographische Messungen der Oberfläche oder andere globale Parameter, die eine Oberfläche charakterisieren.
Sie gilt nicht für ophthalmische Instrumente, welche in die Klasse der Ophthalmometer fallen.
Diese Internationale Norm legt bestimmte Begriffe fest, die im Zusammenhang mit der Charakterisierung der Hornhautoberfläche eine spezielle Bedeutung haben und für die daher eine einheitliche Festlegung für das gesamte Gebiet der Augenheilkunde und alle mit der Materie befassten Personen naheliegend ist.
Diese Internationale Norm legt die Mindestanforderungen an Instrumente und Systeme, die in die Klasse der Hornhauttopographen fallen, fest. Sie definiert Prüfungen und Verfahren, die belegen, dass ein System oder Instrument der Norm entspricht und so als Hornhauttopograph im Sinne der vorliegenden Internationalen Norm gilt. Sie legt weiterhin Prüfungen und Verfahren fest, die die Überprüfung der Technik von Systemen erlauben, die über den Mindestanforderungen für Hornhauttopographen liegen.
Instruments ophtalmiques - Topographes de la cornée (ISO 19980:2005)
Očesna optika – Topografi roženice (ISO 19980:2005)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2005
2þHVQDRSWLND±7RSRJUDILURåHQLFH ,62
Ophthalmic instruments - Corneal topographers (ISO 19980:2005)
Ophthalmische Instrumente - Hornhauttopographen (ISO 19980:2005)
Instruments ophtalmiques - Topographes de la cornée (ISO 19980:2005)
Ta slovenski standard je istoveten z: EN ISO 19980:2005
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN ISO 19980
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2005
ICS 11.040.70
English Version
Ophthalmic instruments - Corneal topographers (ISO
19980:2005)
Instruments ophtalmiques - Topographes de la cornée (ISO Ophthalmische Instrumente - Hornhauttopographen (ISO
19980:2005) 19980:2005)
This European Standard was approved by CEN on 1 August 2005.
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-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19980:2005: E
worldwide for CEN national Members.
Foreword
This document (EN ISO 19980:2005) has been prepared by Technical Committee ISO/TC 172
"Optics and optical instruments" in collaboration with Technical Committee 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 February 2006, and conflicting national
standards shall be withdrawn at the latest by February 2006.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Endorsement notice
The text of ISO 19980:2005 has been approved by CEN as EN ISO 19980:2005 without any
modifications.
INTERNATIONAL ISO
STANDARD 19980
First edition
2005-08-15
Ophthalmic instruments — Corneal
topographers
Instruments ophtalmiques — Topographes de la cornée
Reference number
ISO 19980:2005(E)
©
ISO 2005
ISO 19980:2005(E)
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ii © ISO 2005 – All rights reserved
ISO 19980:2005(E)
Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Requirements . 8
4.1 Area measured . 8
4.2 Measurement sample density. 8
4.3 Measurement and report of performance . 8
4.4 Colour presentation of results . 8
5 Test methods and test devices . 9
5.1 Tests. 9
5.2 Test surfaces. 9
5.3 Data collection, test surfaces . 11
5.4 Analysis of the data. 11
6 Accompanying documents. 13
7 Marking . 13
Annex A (informative) Test surfaces for corneal topographers. 14
Annex B (normative) Standardized displays for corneal topographers. 18
Annex C (normative) Calculation of area-weighting values . 21
Annex D (normative) Test methods for measuring human corneas. 23
Bibliography . 24
ISO 19980:2005(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 2.
The main task of technical committees is to prepare International Standards. 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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 19980 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 7,
Ophthalmic optics and instruments.
iv © ISO 2005 – All rights reserved
INTERNATIONAL STANDARD ISO 19980:2005(E)
Ophthalmic instruments — Corneal topographers
1 Scope
This International Standard is applicable to instruments, systems and methods that are intended to measure
the surface shape of the cornea of the human eye.
NOTE The measurements can be of the curvature of the surface in local areas, three-dimensional topographical
measurements of the surface or other more global parameters used to characterize the surface.
It is not applicable to ophthalmic instruments classified as ophthalmometers.
This International Standard defines certain terms that are specific to the characterization of the corneal shape
so that they may be standardized throughout the field of vision care and have common meaning for all those
who have occasion to participate in this area.
This International Standard specifies minimum requirements for instruments and systems that fall into the
class of corneal topographers. It specifies tests and procedures that will verify that a system or instrument
complies with the standard and so qualifies as a corneal topographer in the meaning of this International
Standard. It specifies certain tests and procedures that will allow the verification of capabilities of systems that
are beyond the minimum required for corneal topographers.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
IEC 60601-1:1988, Medical electrical equipment — Part 1: General requirements for safety
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
corneal apex
location on the corneal surface, where the mean of the local principal curvature is greatest
3.2
corneal eccentricity
e
eccentricity e (3.9) of the conic section which best fits the corneal meridian of interest
NOTE If the meridian is not specified, the corneal eccentricity is that of the flattest corneal meridian (see Table 1 and
Annex A).
ISO 19980:2005(E)
3.3
corneal meridian
θ
curve created by the intersection of corneal surface and a plane which contains the corneal topographer (CT)
axis
NOTE 1 A meridian is identified by the angle, θ, that the plane creating it makes to the horizontal as described by
ISO 8429.
NOTE 2 The value of θ, for a full meridian, takes values from 0° to 180°.
3.3.1
corneal semi-meridian
portion of a full meridian extending from the CT axis toward the periphery in one direction
NOTE The value of θ for a semi-meridian takes values from 0° to 360°.
3.4
corneal shape factor
E
value which specifies the asphericity and type (prolate or oblate) of conic section which best fits a corneal
meridian
NOTE 1 Unless otherwise specified, it refers to the meridian with least curvature (flattest meridian) (see Table 1 and
Annex A).
NOTE 2 Although the magnitude of E is that of the square of the eccentricity and so must always be positive definite,
the sign of E is a convention to signify if an ellipse takes a prolate or oblate orientation.
NOTE 3 The negative value of E is defined by ISO 10110-12 as the conic constant designated by the symbol K. The
negative value of E has also been called asphericity and given the symbol Q.
Table 1 — Conic section descriptors
a
Conic section value of E value of e
Value of p
hyperbola
p < 0 E > 1 e > 1
parabola 0,0 1,0 1,0
b
prolate ellipse
1 > p > 0 0 < E < 1 0 < e < 1
sphere 1,0 0,0 0,0
b
oblate ellipse p > 1 E < 0
0 < e < 1
a
See 3.15.
b
The eccentricity e does not distinguish between prolate and oblate orientations of an
ellipse (see 3.9 and Annex A).
3.5
corneal topographer
instrument or system which measures the shape of corneal surface in a non-contact manner
NOTE A corneal topographer which uses a video camera system and video image processing to measure the
corneal surface by analysing the reflected image created by the corneal surface of a luminous target is also referred to as
a videokeratograph.
3.5.1
optical-sectioning corneal topographer
corneal topographer which measures the corneal surface by analysing multiple optical sections of that surface
2 © ISO 2005 – All rights reserved
ISO 19980:2005(E)
3.5.2
Placido ring corneal topographer
corneal topographer which measures the corneal surface by ana
...
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