SIST EN ISO 8596:2018

SLOVENSKI STANDARD
SIST EN ISO 8596:2018
01-marec-2018
1DGRPHãþD
SIST EN ISO 8596:2009
2þHVQDRSWLND3UHVNXãDQMHRVWULQHYLGD6WDQGDUGQLLQNOLQLþQLRSWRWLSLQQMXQD
SUHGVWDYLWHY,62
Ophthalmic optics - Visual acuity testing - Standard and clinical optotypes and their
presentation (ISO 8596:2017)
Augenoptik - Sehschärfeprüfung - Normsehzeichen und klinische Sehzeichen und ihre
Darbietung (ISO 8596:2017)
Optique ophtalmique - Mesure de l'acuité visuelle - Optotype normalisé et optotypes
cliniques et sa présentation (ISO 8596:2017)
Ta slovenski standard je istoveten z: EN ISO 8596:2018
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
SIST EN ISO 8596:2018 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN ISO 8596:2018

---------------------- Page: 2 ----------------------

SIST EN ISO 8596:2018


EN ISO 8596
EUROPEAN STANDARD

NORME EUROPÉENNE

January 2018
EUROPÄISCHE NORM
ICS 11.040.70 Supersedes EN ISO 8596:2009
English Version

Ophthalmic optics - Visual acuity testing -- Standard and
clinical optotypes and their presentation (ISO 8596:2017)
Optique ophtalmique - Mesure de l'acuité visuelle - Augenoptik - Sehschärfeprüfung - Normsehzeichen
Optotype normalisé et optotypes cliniques et leur und klinische Sehzeichen und ihre Darbietung (ISO
présentation (ISO 8596:2017) 8596:2017)
This European Standard was approved by CEN on 20 November 2017.

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 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
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 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, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8596:2018 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

SIST EN ISO 8596:2018
EN ISO 8596:2018 (E)
Contents Page
European foreword . 3

2

---------------------- Page: 4 ----------------------

SIST EN ISO 8596:2018
EN ISO 8596:2018 (E)
European foreword
This document (EN ISO 8596:2018) 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.
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 July 2018, and conflicting national standards shall be
withdrawn at the latest by July 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 8596:2009.
According to the CEN-CENELEC Internal Regulations, 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, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 8596:2017 has been approved by CEN as EN ISO 8596:2018 without any modification.

3

---------------------- Page: 5 ----------------------

SIST EN ISO 8596:2018

---------------------- Page: 6 ----------------------

SIST EN ISO 8596:2018
INTERNATIONAL ISO
STANDARD 8596
Third edition
2017-11
Ophthalmic optics — Visual acuity
testing — Standard and clinical
optotypes and their presentation
Optique ophtalmique — Mesure de l'acuité visuelle — Optotype
normalisé et optotypes cliniques et leur présentation
Reference number
ISO 8596:2017(E)
©
ISO 2017

---------------------- Page: 7 ----------------------

SIST EN ISO 8596:2018
ISO 8596:2017(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

---------------------- Page: 8 ----------------------

SIST EN ISO 8596:2018
ISO 8596:2017(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 2
4.1 Specifications of the standard optotype. 2
4.2 Visual acuity grades and standard optotype grades . 3
4.3 Test area and spacing between standard optotypes . 4
4.4 Positions of the optotype . 4
4.5 Quality of presentation . 4
4.6 Luminance . 5
5 Test methods . 6
5.1 Viewing distance for distance visual acuity testing . 6
5.2 Criteria for determination and assignment of visual acuity grade . 6
6 Test report . 6
Annex A (informative) Optotypes for clinical investigations . 7
Bibliography .10
© ISO 2017 – All rights reserved iii

---------------------- Page: 9 ----------------------

SIST EN ISO 8596:2018
ISO 8596:2017(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.
The procedures 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 rules 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 identified 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 on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee
SC 7, Ophthalmic optics and instruments.
This third edition cancels and replaces the second edition (ISO 8596:2009), which has been technically
revised.
The main changes compared to the previous edition are as follows:
a) restructuring of technical content into the Clauses 4 and 6 has been applied;
b) terms and definitions with the terms standard optotype, clinical optotype, visual acuity, and
the systems decimal visual acuity, Snellen fraction, LogMAR acuity, and visual acuity grade have
been added;
c) Snellen fraction values in Table 1 have been added;
d) Figure 2 has been added;
e) Annex A has been added.
iv © ISO 2017 – All rights reserved

---------------------- Page: 10 ----------------------

SIST EN ISO 8596:2018
INTERNATIONAL STANDARD ISO 8596:2017(E)
Ophthalmic optics — Visual acuity testing — Standard and
clinical optotypes and their presentation
1 Scope
This document specifies a range of Landolt ring optotypes and describes a method for measuring
distance visual acuity under photopic conditions for the purposes of certification or licensing.
This document is neither intended as a standard for clinical measurements nor for the certification of
blindness or partial sight.
Other optotypes used for clinical investigations are described in Annex A for information.
2 Normative references
The 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 references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3:1973, Preferred numbers — Series of preferred numbers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
standard optotype
Landolt ring
Note 1 to entry: The Landolt ring is specified in Table 1 and Figure 1.
3.2
clinical optotype
optotype other than the standard optotype (3.1) used for measuring visual acuity (3.3)
Note 1 to entry: This definition does not exclude the standard optotype from being used for the same purposes
as a clinical optotype.
Note 2 to entry: Since clinical optotypes can differ greatly in legibility, it is crucial to refer to the standard
optotype whenever the comparability of the results is important. ISO/TR 19498 provides a method for correlation
of clinical optotypes to the standard optotype.
3.3
visual acuity
number characterizing the ability of the visual system to recognize optotypes
Note 1 to entry: Currently, three different scaling systems are used to describe the visual acuity of a patient.
These are decimal visual acuity, Snellen fraction, LogMAR acuity. See Table 1.
© ISO 2017 – All rights reserved 1

---------------------- Page: 11 ----------------------

SIST EN ISO 8596:2018
ISO 8596:2017(E)

3.3.1
decimal visual acuity
reciprocal of the minimum recognizable gap width of a Landolt ring measured in minutes of arc
EXAMPLE A visual acuity of 1,0 is assigned when the smallest Landolt ring recognized by a patient has a gap
width of 1 min of arc measured from the patient’s viewing distance.
3.3.2
Snellen fraction
notation for specifying the angular subtense of an optotype, expressed as a fraction with the numerator
(test distance) being the distance at which visual acuity (3.3) is tested, commonly in m or ft, and the
denominator (normal distance) being the distance at which the critical detail (limb) of the smallest
recognizable optotype subtends 1 min of arc
D
t
V =
Sn
D
n
where
V is the visual acuity, measured as Snellen fraction;
Sn
D is the test distance, measured in m or ft;
t
D is the normal distance, measured in m or ft.
n
EXAMPLE A Snellen fraction
...