SIST EN ISO 15253:2021
(Main)Ophthalmic optics and instruments - Optical and electro-optical devices for enhancing low vision (ISO 15253:2021)
Ophthalmic optics and instruments - Optical and electro-optical devices for enhancing low vision (ISO 15253:2021)
This document is applicable to optical and electro-optical devices specified by the manufacturer for
use by visually impaired persons as low vision aids. This document specifies requirements and test
methods for optical and electro-optical devices specified by the manufacturer for use by visually
impaired persons as low vision devices.
Implantable low vision devices are excluded.
Augenoptik und ophthalmische Instrumente - Optische und elektrooptische vergrößernde Sehhilfen für Sehbehinderte (ISO 15253:2021)
Dieses Dokument gilt für optische und elektrooptische Geräte, die vom Hersteller für die Verwendung durch sehbehinderte Personen als Sehhilfen vorgesehen sind. Dieses Dokument enthält Anforderungen an und Prüfverfahren für optische und elektrooptische Geräte, die vom Hersteller für die Verwendung durch sehbehinderte Personen als Sehhilfen vorgesehen sind.
Implantierte Sehhilfen sind ausgenommen.
Optique et instruments ophtalmiques - Dispositifs optiques et électro-optiques pour malvoyants (ISO 15253:2021)
Le présent document est applicable aux dispositifs optiques et électro-optiques destinés, selon les indications du fabricant, à être utilisés par des personnes malvoyantes comme systèmes d'aide à la vision. Le présent document spécifie les exigences et les méthodes d'essai applicables aux dispositifs optiques et électro-optiques conçus par le fabricant pour servir d'aides à la vision chez les personnes malvoyantes.
Il ne concerne pas les implants oculaires.
Očesna optika in instrumenti - Optične in elektrooptične naprave za izboljšanje slabovidnosti (ISO 15253:2021)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 15253:2021
01-september-2021
Nadomešča:
SIST EN ISO 15253:2001
SIST EN ISO 15253:2001/AC:2001
SIST EN ISO 15254:2009
Očesna optika in instrumenti - Optične in elektrooptične naprave za izboljšanje
slabovidnosti (ISO 15253:2021)
Ophthalmic optics and instruments - Optical and electro-optical devices for enhancing
low vision (ISO 15253:2021)
Augenoptik und ophthalmische Instrumente - Optische und elektrooptische vergrößernde
Sehhilfen für Sehbehinderte (ISO 15253:2021)
Optique et instruments ophtalmiques - Dispositifs optiques et électro-optiques pour
malvoyants (ISO 15253:2021)
Ta slovenski standard je istoveten z: EN ISO 15253:2021
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
SIST EN ISO 15253:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 15253:2021
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SIST EN ISO 15253:2021
EN ISO 15253
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2021
EUROPÄISCHE NORM
ICS 11.040.70 Supersedes EN ISO 15253:2000, EN ISO
15253:2000/AC:2001, EN ISO 15254:2009
English Version
Ophthalmic optics and instruments - Optical and electro-
optical devices for enhancing low vision (ISO 15253:2021)
Optique et instruments ophtalmiques - Dispositifs Augenoptik und ophthalmische Instrumente - Optische
optiques et électro-optiques pour malvoyants (ISO und elektrooptische vergrößernde Sehhilfen für
15253:2021) Sehbehinderte (ISO 15253:2021)
This European Standard was approved by CEN on 28 June 2021.
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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, 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
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15253:2021 E
worldwide for CEN national Members.
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SIST EN ISO 15253:2021
EN ISO 15253:2021 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 15253:2021
EN ISO 15253:2021 (E)
European foreword
This document (EN ISO 15253:2021) 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 January 2022, and conflicting national standards shall
be withdrawn at the latest by January 2022.
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 15253:2000, EN ISO 15253:2000/AC:2001 and EN ISO 15254:2009.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN websites.
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, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 15253:2021 has been approved by CEN as EN ISO 15253:2021 without any modification.
3
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SIST EN ISO 15253:2021
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SIST EN ISO 15253:2021
INTERNATIONAL ISO
STANDARD 15253
Second edition
2021-06
Ophthalmic optics and instruments —
Optical and electro-optical devices for
enhancing low vision
Optique et instruments ophtalmiques — Dispositifs optiques et
électro-optiques pour malvoyants
Reference number
ISO 15253:2021(E)
©
ISO 2021
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SIST EN ISO 15253:2021
ISO 15253:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
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SIST EN ISO 15253:2021
ISO 15253:2021(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification . 9
4.1 Optical devices . 9
4.1.1 Distance vision . . 9
4.1.2 Near and intermediate vision . 9
4.1.3 Retinal illumination reduction or contrast enhancement . 9
4.2 Electro-optical devices . 9
5 Requirements . 9
5.1 General . 9
5.1.1 Risk assessment and management . 9
5.1.2 Materials . 9
5.1.3 Dimensions and weight . 9
5.1.4 Flammability/Ignitability.10
5.1.5 Resistance to perspiration .10
5.1.6 Robustness .10
5.1.7 Resistance to drop .10
5.2 Optical devices .10
5.2.1 Spatial resolution .10
5.2.2 Equivalent power (applies to optical devices designed for near or
intermediate use) .10
5.2.3 Magnification .11
5.2.4 Exit image distance (applies to stand magnifiers) .11
5.2.5 Entrance pupil diameter (applies to telescopes) .12
5.2.6 Transmittance .12
5.2.7 Image relocation .12
5.3 Electro-optical devices .12
5.3.1 Display size .12
5.3.2 Ambient temperatures . . .12
5.3.3 Image characteristics .12
5.3.4 Object (XY) table .13
5.3.5 Electro-optical device working distance .13
5.3.6 Text to speech system .13
5.3.7 Electrical requirements .13
6 Test methods .13
6.1 General .13
6.2 Optical devices .14
6.2.1 Spatial resolution test .14
6.2.2 Equivalent power – Magnifiers .18
6.2.3 Angular magnification – Telescopes .18
6.2.4 Transverse magnification – Stand magnifiers .18
6.2.5 Lateral variation of magnification test .18
6.2.6 Exit image distance – Stand magnifiers .18
6.3 Electro-optical devices .18
6.3.1 Display magnification test .18
6.3.2 Uniformity of magnification .18
7 Information to be provided by the manufacturer .18
7.1 Marking .18
7.2 Instructions for use .20
© ISO 2021 – All rights reserved iii
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SIST EN ISO 15253:2021
ISO 15253:2021(E)
Annex A (informative) Determination of lateral variation of magnification .21
Bibliography .26
iv © ISO 2021 – All rights reserved
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SIST EN ISO 15253:2021
ISO 15253:2021(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, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 170, Ophthalmic optics, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition of ISO 15253:2000 and the second edition of
ISO 15254:2009, which have been technically revised.
The main changes compared to the previous edition are as follows:
— merger of ISO 15253 and ISO 15254;
— revision of normative references;
— revision and re-organisation of terms and definitions;
— addition of new requirements for filters and tints, image relocation, and text to speech;
— editorial revision of the document.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2021 – All rights reserved v
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SIST EN ISO 15253:2021
ISO 15253:2021(E)
Introduction
This document represents the merger of two earlier related standards for low vision devices – one for
optical devices only (first edition of ISO 15253) and another for electro-optical devices (ISO 15254) –
and updating of terms, definitions, and requirements. It also includes new requirements for
— filters and tints, such as for users with extreme light sensitivity or reduced contrast sensitivity,
independent of visual acuity or visual field loss,
— image relocation, such as with prisms or mirrors for users with visual field loss or eye- or head-
movement restriction, and
— text to speech for electro-optical devices that offer such capability.
The reader is reminded that the requirements within this document apply to the manufacturer of low
vision devices. While the requirements can also pertain to how a particular device will function for the
low vision user, some factors and variables about the user may not be known to the manufacturer and
thus specific requirements cannot be made. For example, the system resolution of an electro-optical
device is governed by pixel size and density for both the camera and display, while the spatial resolution
for the user depends on the size of the display and the distance at which the user views the display.
vi © ISO 2021 – All rights reserved
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SIST EN ISO 15253:2021
INTERNATIONAL STANDARD ISO 15253:2021(E)
Ophthalmic optics and instruments — Optical and electro-
optical devices for enhancing low vision
1 Scope
This document is applicable to optical and electro-optical devices specified by the manufacturer for
use by visually impaired persons as low vision aids. This document specifies requirements and test
methods for optical and electro-optical devices specified by the manufacturer for use by visually
impaired persons as low vision devices.
Implantable low vision devices are excluded.
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 12312-1, Eye and face protection — Sunglasses and related eyewear — Part 1: Sunglasses for general
use
ISO 12870, Ophthalmic optics — Spectacle frames — Requirements and test methods
ISO 14889, Ophthalmic optics — Spectacle lenses — Fundamental requirements for uncut finished lenses
ISO 14971, Medical devices — Application of risk management to medical devices
ISO 15004-1, Ophthalmic instruments — Fundamental requirements and test methods — Part 1: General
requirements applicable to all ophthalmic instruments
ISO 15004-2, Ophthalmic instruments — Fundamental requirements and test methods — Part 2: Light
hazard protection
IEC 60601-1, Medical electrical equipment — Part 1: General requirements for basic safety and essential
performance
IEC 60601-1-2, Medical electrical equipment — Part 1-2: General requirements for basic safety and essential
performance — Collateral standard: Electromagnetic disturbances — Requirements and tests
IEC 60601-1-3, Medical Electrical Equipment — Part 1-3: General Requirements for Basic Safety And
Essential Performance — Collateral Standard: Radiation Protection In Diagnostic X-Ray Equipment
IEC 60695-2-11, Fire Hazard Testing — Part 2-11: Glowing/Hot-Wire Based Test Methods — Glow-Wire
Flammability Test Method for End-Products (GWEPT)
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:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org
© ISO 2021 – All rights reserved 1
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SIST EN ISO 15253:2021
ISO 15253:2021(E)
3.1
low vision device
apparatus that alters or enhances the image viewed by a person having low vision
3.1.1
optical low vision device
optical device
lens or lens system, prism, or mirror, or combination of such optical components, that alters image
characteristics, such as vergence, size, and/or position
Note 1 to entry: Image relocation using a prism, whether ground in or temporary (e.g., Fresnel), is commonly
expressed in centimetres per metre or prism dioptres.
Note 2 to entry: Image relocation using a mirror is commonly expressed in degrees.
3.1.2
electro-optical low vision device
opto-electronic low vision device
electro-optical device
device or system that produces an altered or enhanced image through the interaction between light
from the object and an electronic system
Note 1 to entry: The device minimally consists of a camera and a monitor or display, but can contain additional
components such as a computer, display control interface, projector, speakers, tactile output, narrow-beam light
source, scanner, and software.
Note 2 to entry: In addition to computer-based systems, common configurations and terms for electro-optical
devices are video magnifier and closed-circuit television (CCTV), with which the image is displayed or projected
at some distance removed from the user’s spectacle plane, and head-mounted (also known as head-up) display,
with which the image is presented on a display at or near the user’s spectacle plane or projected directly into the
user’s eye.
3.1.3
filter
tinted lens
optical component that absorbs and/or reflects light in order to reduce the amount of light transmitted
to the user’s eye
3.1.3.1
neutral density filter
filter (3.1.3) designed to reduce the amount of light by the same percentage for each wavelength across
the visible spectrum
3.1.3.2
coloured tint
filter (3.1.3) that selectively reduces the amount of light transmitted for some wavelengths relative to
that transmitted for other wavelengths
Note 1 to entry: Examples of coloured tints include cut-off, bandpass, and notch filters.
3.2
magnification
ratio between a dimension of the image when a low vision device (3.1) is in use and the corresponding
dimension when the object is viewed without the device
Note 1 to entry: Dimension can be angular or linear.
2 © ISO 2021 – All rights reserved
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SIST EN ISO 15253:2021
ISO 15253:2021(E)
3.2.1
angular magnification
ratio of the angle subtended by the image of the object when viewed using a low vision device (3.1) to the
angle subtended by the object alone at a viewing point of reference, such as the entrance pupil of the eye
Note 1 to entry: Angular magnification is used primarily for afocal telescopic low vision devices. It also applies in
part to magnifiers that are positioned at distances removed from the spectacle plane.
3.3
magnifier
lens system designed to change the size of the image of a near object
Note 1 to entry: The magnifier can be a simple single element or a compound multiple-element system.
3.3.1
hand magnifier
hand-held magnifier
magnifier (3.3) intended to be positioned and supported by the user's hand and without artificial
support
3.3.2
stand magnifier
magnifier (3.3) in which a support positions the optical system at a fixed or adjustable distance from
the object to be viewed
3.3.3
head-mounted magnifier
magnifier (3.3) mounted in a device that is supported on the head
3.3.4
spectacle-mounted magnifier
magnifier (3.3) mounted in a device that attaches to a spectacle frame
3.3.5
spectacle magnifier
spectacle microscope
spectacle lenses having greater power for near focus than found in typical spectacle corrections,
creating retinal image magnification primarily by allowing for relative distance magnification
Note 1 to entry: In addition to relative distance magnification, some usually small amount of magnification can
result from the parameters of the lens, such as base curve, centre thickness, and refractive index.
3.4
telescope
optical system composed of two separated lenses (or lens systems), the objective and the eyepiece, that
forms a magnified image of a distant object when the eyepiece is the higher powered lens (or system)
Note 1 to entry: In its afocal adjustment, the second (back) focal point of the objective lies at the first (front)
focal point of the eyepiece, so that light from a distant object, entering the objective with zero vergence, exits the
eyepiece with zero vergence. This is the condition for a user wearing full correction for refractive error viewing a
very distant object clearly through the telescope.
Note 2 to entry: A telescope provides angular magnification, which in its afocal adjustment can be calculated by
the negative of the ratio of the equivalent power of the eyepiece to the equivalent power of the objective.
3.4.1
entrance pupil diameter
clear aperture of the telescopic objective
Note 1 to entry: Entrance pupil diameter is expressed in millimetres.
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SIST EN ISO 15253:2021
ISO 15253:2021(E)
3.4.2
focusable telescope
telescope for which the separation between the objective and eyepiece can be changed to compensate
for a range of object distances and/or to compensate for uncorrected spherical refractive error
3.5
telemicroscope
near-vision telescope
telescope adapted for viewing near or intermediate objects
3.5.1
reading cap
positive optical element placed in front of the telescopic objective to adapt the device for viewing a near
or intermediate object
Note 1 to entry: Reading cap power is expressed in dioptres.
Note 2 to entry: In a fixed-focus afocal telescope, the reading cap is a removable lens.
Note 3 to entry: In a fixed-focus telemicroscope, the reading cap is incorporated into the objective power.
Note 4 to entry: In a focusable telescope, a portion of the objective power functions as the reading cap. This
reduces the objective power that remains, thus creating a “new” afocal telescope with slightly greater angular
magnification.
3.6
field expander
reverse telescope
minifier
device that reduces the apparent field of view so that it is smaller than the user’s unaided field of view
Note 1 to entry: Apparent field of view is the angle subtended by the field as viewed through a telesc
...
SLOVENSKI STANDARD
oSIST prEN ISO 15253:2020
01-december-2020
Očesna optika in instrumenti - Optične in elektrooptične naprave za izboljšanje
slabovidnosti (ISO/DIS 15253:2020)
Ophthalmic optics and instruments - Optical and electro-optical devices for enhancing
low vision (ISO/DIS 15253:2020)
Augenoptik und ophthalmische Instrumente - Optische und elektro-optische
vergrößernde Sehhilfen für Sehbehinderte (ISO/DIS 15253:2020)
Optique et instruments ophtalmiques - Dispositifs optiques et électro optiques pour
malvoyants (ISO/DIS 15253:2020)
Ta slovenski standard je istoveten z: prEN ISO 15253
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
oSIST prEN ISO 15253:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 15253:2020
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oSIST prEN ISO 15253:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 15253
ISO/TC 172/SC 7 Secretariat: DIN
Voting begins on: Voting terminates on:
2020-10-07 2020-12-30
Ophthalmic optics and instruments — Optical and electro-
optical devices for enhancing low vision
Optique et instruments ophtalmiques — Dispositifs optiques pour malvoyants
ICS: 11.040.70
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 15253:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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oSIST prEN ISO 15253:2020
ISO/DIS 15253:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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oSIST prEN ISO 15253:2020
ISO/DIS 15253:2020(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification . 9
4.1 Optical devices . 9
4.1.1 Distance vision . . 9
4.1.2 Near and intermediate vision . 9
4.1.3 Retinal illumination reduction or contrast enhancement . 9
4.2 Electro-optical devices . 9
5 Requirements . 9
5.1 General . 9
5.1.1 Risk assessment and management . 9
5.1.2 Materials . 9
5.1.3 Dimensions and weight .10
5.1.4 Flammability/Ignitability.10
5.1.5 Resistance to perspiration .10
5.1.6 Robustness .10
5.1.7 Resistance to drop .10
5.2 Optical devices .10
5.2.1 Spatial resolution .10
5.2.2 Equivalent power (applies to optical devices designed for near or
intermediate use) .11
5.2.3 Magnification .11
5.2.4 Exit image distance (applies to stand magnifiers) .12
5.2.5 Entrance pupil diameter (applies to telescopes) .12
5.2.6 Transmittance .12
5.2.7 Image relocation .12
5.3 Electro-optical devices .12
5.3.1 Display size .12
5.3.2 Ambient temperatures . . .12
5.3.3 Image characteristics .12
5.3.4 Object (XY) table .13
5.3.5 Working distance .13
5.3.6 Text to speech .13
5.3.7 Electrical requirements .13
6 Test methods .13
6.1 General .13
6.2 Optical devices .14
6.2.1 Spatial resolution test .14
6.2.2 Equivalent power – Magnifiers .17
6.2.3 Angular magnification – Telescopes .17
6.2.4 Transverse magnification – Stand magnifiers .17
6.2.5 Lateral variation of magnification test .17
6.2.6 Exit image distance – Stand magnifiers .18
6.3 Electro-optical devices .18
6.3.1 Display magnification test .18
6.3.2 Uniformity of magnification .18
7 Information to be provided by the manufacturer .18
7.1 Marking .18
7.2 Instructions for use .18
© ISO 2020 – All rights reserved iii
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oSIST prEN ISO 15253:2020
ISO/DIS 15253:2020(E)
7.2.1 General.18
7.2.2 Optical devices .19
7.2.3 Electro-optical devices.19
Annex A (informative) Determination of lateral variation of magnification .20
iv © ISO 2020 – All rights reserved
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oSIST prEN ISO 15253:2020
ISO/DIS 15253:2020(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.
This edition cancels and replaces the first edition (ISO 15253:2000) and the second edition of ISO 15254
(ISO 15254:2009), which both have been technically revised.
The main changes compared to the previous edition are as follows:
— merger of ISO 15253 and ISO 15254;
— revision of normative references;
— revision and re-organisation of terms and definitions;
— addition of new requirements for filters and tints, image relocation, and text to speech;
— editorial revision of the document.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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Introduction
This document represents the merger of two earlier related standards for low vision devices – one for
optical devices only (previous ISO 15253) and another for electro-optical devices (ISO 15254) – and
updating of terms, definitions, and requirements. It also includes new requirements for
— filters and tints, such as for users with extreme light sensitivity or reduced contrast sensitivity,
independent of visual acuity or visual field loss;
— image relocation, such as with prisms or mirrors for users with visual field loss or eye- or head-
movement restriction; and
— text to speech for electro-optical devices that offer such capability.
The reader is reminded that the requirements within this document apply to the manufacturer of low
vision devices. While the requirements can also pertain to how a particular device will function for the
low vision user, some factors and variables about the user may not be known to the manufacturer and
thus specific requirements cannot be made. For example, the system resolution of an electro-optical
device is governed by pixel size and density for both the camera and display, while the spatial resolution
for the user depends on the size of the display and the distance at which the user views the display.
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DRAFT INTERNATIONAL STANDARD ISO/DIS 15253:2020(E)
Ophthalmic optics and instruments — Optical and electro-
optical devices for enhancing low vision
1 Scope
This document applies to optical and electro-optical devices specified by the manufacturer for use by
visually impaired persons as low vision aids. This document contains requirements and test methods
for optical and electro-optical devices specified by the manufacturer for use by visually impaired
persons as low vision devices.
Implanted low vision devices are excluded.
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.
EN 55022, Information technology equipment — Radio disturbance characteristics — Limits and methods
of measurement (IEC/CISPR 22:2005, modified + A1: 2005)
EN 60950-1, Information technology equipment — Safety — Part 1: General requirements
ISO 12312-1, Eye and face protection — Sunglasses and related eyewear — Part 1: Sunglasses for general use
ISO 12870, Ophthalmic optics — Spectacle frames — Requirements and test methods
ISO 14889, Ophthalmic optics — Spectacle lenses — Fundamental requirements for uncut finished lenses
ISO 14971, Medical devices — Application of risk management to medical devices
ISO 15004-1, Ophthalmic instruments — Fundamental requirements and test methods — Part 1: General
requirements applicable to all ophthalmic instruments
ISO 15004-2, Ophthalmic instruments — Fundamental requirements and test methods — Part 2: Light
hazard protection
IEC 60601-1, Medical electrical equipment — Part 1: General requirements for basic safety and essential
performance
IEC 60601-1-2, Medical electrical equipment — Part 1-2: General requirements for basic safety and essential
performance — Collateral standard: Electromagnetic disturbances — Requirements and tests
IEC 60601-1-3, Medical Electrical Equipment — Part 1-3: General Requirements for Basic Safety And
Essential Performance — Collateral Standard: Radiation Protection In Diagnostic X-Ray Equipment
IEC 60695-2-11, Fire Hazard Testing — Part 2-11: Glowing/Hot-Wire Based Test Methods — Glow-Wire
Flammability Test Method for End-Products (GWEPT)
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
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— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
low vision device
apparatus that alters or enhances the image viewed by a person having low vision
3.1.1
optical low vision device
lens or lens system, prism, or mirror, or combination of such optical components, that alters image
characteristics, such as vergence, size, and/or position
Note 1 to entry: Image relocation using a prism, whether ground in or temporary (e.g., Fresnel), is commonly
expressed in centimetres per metre or prism dioptres.
Note 2 to entry: Image relocation using a mirror is commonly expressed in degrees.
3.1.2
electro-optical low vision device
opto-electronic low vision device
device or system that produces an altered or enhanced image through the interaction between light
from the object and an electronic system
Note 1 to entry: The device minimally consists of a camera and a monitor or display, but can contain additional
components such as a computer, display control interface, projector, speakers, tactile output, narrow-beam light
source, scanner, and software.
Note 2 to entry: In addition to computer-based systems, common configurations and terms for electro-optical
low vision devices are video magnifier and closed-circuit television (CCTV), with which the image is displayed or
projected at some distance removed from the user’s spectacle plane, and head-mounted (a.k.a. head-up) display,
with which the image is presented on a display at or near the user’s spectacle plane or projected directly into the
user’s eye.
3.1.3
filter
tinted lens
optical component that absorbs and/or reflects light in order to reduce the amount of light transmitted
to the user’s eye
3.1.3.1
neutral density filter
filter designed to reduce the amount of light by the same percentage for each wavelength across the
visible spectrum
3.1.3.2
coloured tint
filter that selectively reduces the amount of light transmitted for some wavelengths relative to that
transmitted for other wavelengths
Note 1 to entry: Examples of coloured tints include cut-off, bandpass, and notch filters.
3.2
magnification
ratio between a dimension of the image when a low vision device is in use and the corresponding
dimension when the object is viewed without the device
Note 1 to entry: Dimension can be angular or linear.
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3.2.1
angular magnification
ratio of the angle subtended by the image of the object when viewed using a low vision device to the
angle subtended by the object alone at a viewing point of reference, such as the entrance pupil of the eye
Note 1 to entry: Angular magnification is used primarily for afocal telescopic low vision devices. It also applies in
part to magnifiers that are positioned at distances removed from the spectacle plane.
3.2.2
retinal image magnification
total magnification that is obtained when using a low vision device and/or viewing technique, calculated
as the product of the angular, relative distance, and relative size magnifications.
Note 1 to entry: Viewing techniques include changing viewing distance (i.e., relative distance magnification) and
changing font or object size (i.e., relative size magnification). Depending on the low vision device and how it is
used, a specific change can result in an increase or decrease in image size compared to that dimension when the
device is not used.
3.3
magnifier
lens system designed to change the size of the image of a near object
Note 1 to entry: The magnifier may be a simple single element or a compound multiple-element system.
3.3.1
hand magnifier
hand-held magnifier
magnifier intended to be positioned and supported by the user's hand and without artificial support
3.3.2
stand magnifier
magnifier in which a support positions the optical system at a fixed or adjustable distance from the
object to be viewed
3.3.3
head-mounted magnifier
magnifier mounted in a device that is supported on the head
3.3.4
spectacle-mounted magnifier
magnifier mounted in a device that attaches to a spectacle frame
3.3.5
spectacle magnifier
spectacle microscope
spectacle lenses having greater power for near focus than found in typical spectacle corrections,
creating retinal image magnification primarily by allowing for relative distance magnification
Note 1 to entry: In addition to relative distance magnification, some usually small amount of magnification can
result from the parameters of the lens, such as base curve, centre thickness, and refractive index.
3.4
telescope
optical system composed of two separated lenses (or lens systems), the objective and the eyepiece, that
forms a magnified image of a distant object when the eyepiece is the higher powered lens (or system)
Note 1 to entry: In its afocal adjustment, the second (back) focal point of the objective lies at the first (front)
focal point of the eyepiece, so that light from a distant object, entering the objective with zero vergence, exits the
eyepiece with zero vergence. This is the condition for a user wearing full correction for refractive error viewing a
very distant object clearly through the telescope.
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Note 2 to entry: A telescope provides angular magnification, which in its afocal adjustment can be calculated by
the negative of the ratio of the equivalent power of the eyepiece to the equivalent power of the objective.
3.4.1
entrance pupil diameter
clear aperture of the telescopic objective
Note 1 to entry: Entrance pupil diameter is expressed in millimetres.
3.4.2
focusable telescope
telescope for which the separation between the objective and eyepiece can be changed to compensate
for a range of object distances and/or to compensate for uncorrected spherical refractive error
3.5
telemicroscope
near-vision telescope
telescope adapted for viewing near or intermediate objects
3.5.1
reading cap
positive optical element placed in front of the telescopic objective to adapt the device for viewing a near
or intermediate object
Note 1 to entry: Reading cap power is expressed in dioptres.
Note 2 to entry: In a fixed-focus afocal telescope, the reading cap is a removable lens.
Note 3 to entry: In a fixed-focus telemicroscope, the reading cap is incorporated into the objective power.
Note 4 to entry: In a focusable telescope, a portion of the objective power functions as the reading cap. This
reduces the objective power that remains, thus creating a “new” afocal telescope with slightly greater angular
magnification.
3.6
field expander
reverse telescope
minifier
device that reduces the apparent field of view so that it is smaller than the user’s unaided field of view
Note 1 to entry: Apparent field of view is the angle subtended by the field as viewed through a telescope.
3.7
spatial resolution
smallest separation between two details in the object for which they can be recognised as being
separate under a given set of conditions
3.8
field of view
extent of the object plane visible through, or imaged by, a device
Note 1 to entry: See entries below for definitions of field of view for specific types of devices.
3.8.1
resolvable field of view
field of view within which the device is capable of resolving required details
3.9 Parameters for magnifiers
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3.9.1
optical dimensions
zone of optical dimensions
optical zone of magnifier
linear size of the lens of a magnifier that is visible when mounted
Note 1 to entry: Optical dimensions are expressed in millimetres.
3.9.2
optical axis
line connecting the centres of curvature of the surfaces of an optical system, along which there is
symmetry and zero induced prism
3.9.3
equivalent focal length
distance between a focal point and the corresponding principal plane, measured along the optical axis
SEE: Figure 1.
Note 1 to entry: First focal length is measured from the first principal plane to the first (front) focal point.
Note 2 to entry: Second focal length is measured from the second principal plane to the second (back) focal point.
3.9.4
equivalent power
reciprocal of the equivalent focal length in air measured in metres
Note 1 to entry: Equivalent power is expressed in dioptres, or reciprocal metres.
Key
1 first focal length F first (front) focal point
2 second focal length F’ second (back) focal point
H first principal plane
H’ second principal plane
Figure 1 — Illustration of focal lengths
3.9.5
working distance
distance between the front vertex of the magnifier and the object being viewed
SEE: Figure 2.
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3.9.6
exit image distance
vertex image distance
distance between the back vertex of the magnifier and the virtual image formed by the magnifier when
the object is placed in the designated position
SEE: Figure 2.
Note 1 to entry: Exit image distance is especially useful for stand magnifiers.
3.9.7
viewing distance
distance between the image formed by the magnifier and the spectacle plane of the user
SEE: Figure 2.
Key
1 object plane y object size
2 image plane y’ image size
3 spectacle plane
4 working dis
...
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