EN ISO 21987:2009

SLOVENSKI STANDARD
01-januar-2010
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Ophthalmic optics - Mounted spectacle lenses (ISO 21987:2009)
Augenoptik - Fertig montierte Korrektionsbrillengläser (ISO 21987:2009)
Optique ophtalmique - Verres ophtalmiques montés (ISO 21987:2009)
Ta slovenski standard je istoveten z: EN ISO 21987:2009
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 21987
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2009
ICS 11.040.70
English Version
Ophthalmic optics - Mounted spectacle lenses (ISO
21987:2009)
Optique ophtalmique - Verres ophtalmiques montés (ISO Augenoptik - Fertig montierte Korrektionsbrillengläser (ISO
21987:2009) 21987:2009)
This European Standard was approved by CEN on 17 September 2009.

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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21987:2009: E
worldwide for CEN national Members.

Contents Page
Foreword .3
Annex ZA (informative)  Relationship between this International Standard and the Essential
Requirements of EU Directive 93/42/EEC .4

Foreword
This document (EN ISO 21987:2009) 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 April 2010, and conflicting national standards shall be withdrawn at the
latest by April 2010.
Attention is drawn to the possibility that some of the elements 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.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive.
For relationship with EU Directive, see informative Annex ZA, which is an integral part of this document.
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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 21987:2009 has been approved by CEN as a EN ISO 21987:2009 without any modification.
Annex ZA
(informative)
Relationship between this International Standard and the Essential
Requirements of EU Directive 93/42/EEC
This International Standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association to provide one means of conforming to Essential Requirements of
the New Approach Directive 93/42/EEC, Medical devices: General.
Once this standard is cited in the Official Journal of the European Union under that Directive and has been
implemented as a national standard in at least one Member State, compliance with the normative clauses of
this standard given in Table ZA.1 confers, within the limits of the scope of this standard, a presumption of
conformity with the corresponding Essential Requirements of that Directive and associated EFTA regulations.
Table ZA.1 - Correspondence between this International Standard and Directive 93/42/EEC
Clause(s)/sub-clause(s) of Essential requirements (ERs) of
Qualifying remarks/Notes
this International Standard EU Directive 93/42/EEC
These ERs are covered by
5.2 1, 2, 3, 4, 6, 6a), 7.1, 9.2, 9.3
normative reference to ISO
14889:2003.
5.3, 5.4, 5.5 3
These ERs are covered by clause 7,
7, 8 13.1, 13.3
and by the normative reference to
ISO 14889:2003 in clause 8.
NOTE    ER 13.3.a) is only partly addressed in ISO 14889:2003.

WARNING: Other requirements and other EU Directives may be applicable to the products falling within the
scope of this standard.
INTERNATIONAL ISO
STANDARD 21987
First edition
2009-10-01
Ophthalmic optics — Mounted spectacle
lenses
Optique ophtalmique — Verres ophtalmiques montés

Reference number
ISO 21987:2009(E)
©
ISO 2009
ISO 21987:2009(E)
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ii © ISO 2009 – All rights reserved

ISO 21987:2009(E)
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Classification .2
5 Requirements.2
5.1 Reference temperature .2
5.2 Lenses used in manufacturing complete spectacles .2
5.3 Optical requirements.2
5.4 Thickness tolerance .6
5.5 Positioning tolerances.6
6 Test methods .8
6.1 General .8
6.2 Measurement method for the back vertex power of single-vision lenses and the distance
portion of multifocal and progressive-power lenses and near portion of degressive-power
lenses.8
6.3 Measurement method for cylinder axis.8
6.4 Addition power measurement.8
6.5 Method for measuring position and tilt.10
6.6 Material and surface quality .10
6.7 Prism imbalance (relative prism error) measurement method for pairs of single-vision and
multifocal lenses .10
7 Marking for progressive-power and degressive-power lenses .10
7.1 Permanent marking .10
7.2 Non-permanent marking.11
8 Identification .11
9 Reference to ISO 21987.11
Annex A (informative) Material and surface quality .12
Annex B (informative) Recommendations on mounting.13
Annex C (informative) Alternative methods for measuring prism imbalance (relative prism error)
for pairs of single-vision and multifocal lenses.15
Bibliography.17

ISO 21987:2009(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 21987 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 7,
Ophthalmic optics and instruments.

iv © ISO 2009 – All rights reserved

INTERNATIONAL STANDARD ISO 21987:2009(E)

Ophthalmic optics — Mounted spectacle lenses
1 Scope
This International Standard specifies requirements for mounted spectacle lenses relative to the prescription
order.
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.
ISO 7944, Optics and optical instruments — Reference wavelengths
ISO 8429, Optics and optical instruments — Ophthalmology — Graduated dial scale
ISO 8598, Optics and optical instruments — Focimeters
ISO 8624, Ophthalmic optics — Spectacle frames — Measuring system and terminology
ISO 8980-1, Ophthalmic optics — Uncut finished spectacle lenses — Part 1: Specifications for single-vision
and multifocal lenses
ISO 8980-2, Ophthalmic optics — Uncut finished spectacle lenses — Part 2: Specifications for progressive-
power lenses
ISO 8980-3, Ophthalmic optics — Uncut finished spectacle lenses — Part 3: Transmittance specifications and
test methods
ISO 8980-4, Ophthalmic optics — Uncut finished spectacle lenses — Part 4: Specifications and test methods
for anti-reflective coatings
ISO 8980-5, Ophthalmic optics — Uncut finished spectacle lenses — Part 5: Minimum requirements for
spectacle lens surfaces claimed to be abrasion-resistant
ISO 13666, Ophthalmic optics — Spectacle lenses — Vocabulary
ISO 14889:2003, Ophthalmic optics — Spectacle lenses — Fundamental requirements for uncut finished
lenses
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13666 apply.
ISO 21987:2009(E)
4 Classification
Finished, mounted lenses are classified as follows:
a) single-vision finished lenses;
b) multifocal finished lenses;
c) progressive-power and degressive-power finished lenses.
5 Requirements
5.1 Reference temperature
The tolerances shall apply at a temperature of 23 °C ± 5 °C.
5.2 Lenses used in manufacturing complete spectacles
Lenses used in manufacturing complete spectacles shall meet the requirements of ISO 14889:2003, 4.1, 4.2,
4.3.1, 4.3.2 and 4.5. Lenses shall also have been shown to meet the requirements ISO 14889:2003, 4.4
unless a national standard or law specifies mechanical strength requirements, in which case the national
standard or law will take precedence.
ISO 14889:2003, 4.1 requires that the uncut finished lenses used in manufacturing complete spectacles
comply with the relevant parts of ISO 8980.
Lenses in mounted spectacles shall also comply with other requirements of the prescription order not included
in this International Standard.
5.3 Optical requirements
5.3.1 General
The optical characteristics shall be determined using a focimeter complying with ISO 8598.
Where the power is measured in the presence of more than 0,50 ∆ the optical power shall be the off-axis
power.
The optical tolerances shall apply at the reference point(s) of the lenses at either of the reference wavelengths
specified in ISO 7944.
If the manufacturer has applied corrections to compensate for the “as-worn” position, then the tolerances shall
apply to this “as-worn” corrected dioptric power.
5.3.2 Back vertex power tolerance
The tolerances in Table 1 apply to all single-vision lenses and the distance portion of multifocal lenses,
including those with aspherical or atoroidal surfaces. The tolerances in Table 2 apply to the distance portion of
progressive-power lenses and the near portion of degressive-power lenses. The back vertex power shall be
measured using the method described in 6.2.
5.3.3 Cylinder axis direction tolerance
The direction of the cylinder axis shall be measured using the method described in 6.3, and shall be specified
in accordance with ISO 8429. The tolerances on the direction of the cylinder axis are specified in Table 3.
2 © ISO 2009 – All rights reserved

ISO 21987:2009(E)
NOTE 1 To allow for some tolerance in mounting, the tolerance on the direction of cylinder axis has generally been
increased over the tolerances found in the ISO uncut finished lens standards ISO 8980-1 and ISO 8980-2.
NOTE 2 Compensation for the “as-worn” position might result in cylinder powers of less than 0,12 D, in which case
there are no applicable axis tolerances.
5.3.4 Addition power tolerance for multifocal and progressive-power lenses
The addition power shall be measured using the method described in 6.4. The tolerances on addition power
are specified in Table 4.
Table 1 — Tolerances on the back vertex power of single-vision and multifocal lenses
Values in dioptres
Tolerance of the cylindrical power
Power of principal meridian Tolerance on the back
with higher absolute back vertex power of each
W 0,00 and > 0,75 and > 4,00 and
> 6,00
vertex power principal meridian
u 0,75 u 4,00 u 6,00
W 0,00 and u 3,00 ± 0,12 ± 0,09 ± 0,12 ± 0,18 —
> 3,00 and u 6,00 ± 0,12 ± 0,12 ± 0,12 ± 0,18 ± 0,25
> 6,00 and u 9,00 ± 0,12 ± 0,12 ± 0,18 ± 0,18 ± 0,25
> 9,00 and u12,00 ± 0,18 ± 0,12 ± 0,18 ± 0,25 ± 0,25
> 12,00 and u 20,00 ± 0,25 ± 0,18 ± 0,25 ± 0,25 ± 0,25
> 20,00 ± 0,37 ± 0,25 ± 0,25 ± 0,37 ± 0,37

Table 2 — Tolerances on the back vertex power of progressive- and degressive-power lenses
Values in dioptres
Tolerance of the cylindrical power
Power of principal meridian Tolerance on the back
with higher absolute back vertex power of each
W 0,00 and > 0,75 and > 4,00 and
> 6,00
vertex power principal meridian
u 0,75 u 4,00 u 6,00
W 0,00 and u 6,00 ± 0,12 ± 0,12 ± 0,18 ± 0,18 ± 0,25
> 6,00 and u 9,00 ± 0,18 ± 0,18 ± 0,18 ± 0,18 ± 0,25
> 9,00 and u12,00 ± 0,18 ± 0,18 ± 0,18 ± 0,25 ± 0,25
> 12,00 and u 20,00 ± 0,25 ± 0,18 ± 0,25 ± 0,25 ± 0,25
> 20,00 ± 0,37 ± 0,25 ± 0,25 ± 0,37 ± 0,37

Table 3 — Tolerances on the direction of cylinder axis
W 0,125 > 0,25 > 0,50 > 0,75 > 1,50
Absolute cylindrical power
and and and and and > 2,50
dioptres
u 0,25 u 0,50 u 0,75 u 1,50 u 2,50
Tolerance on the axis direction
± 16 ± 9 ± 6 ± 4 ± 3 ± 2
degrees
Table 4 — Tolerances on the addition power for multifocal and progressive-power lenses
Values in dioptres
Value of the addition power u 4,00 > 4,00
Tolerance ± 0,12 ± 0,18
ISO 21987:2009(E)
5.3.5 Prism imbalance (relative prism error) for pairs of single-vision and multifocal lenses
After neutralizing or allowing for any prescribed prism, the tolerances as given in Table 5 shall be met when
tested in accordance with the method given in 6.7.
To determine the prism imbalance:
1) resolve any ordered prism to its horizontal and vertical components;
2) find four principal powers (two in each lens);
3) identify the minimum absolute power from the four principal powers;
4) enter Figure 1 with that power (the X-axis) and find horizontal imbalance tolerance (the Y-axis), using
the curve representing the relevant range that contains the higher value ordered prism component;
5) enter Figure 2 with that power (the X-axis) and find vertical imbalance tolerance (the Y-axis), using
the curve representing the relevant range that contains the higher value ordered prism component.
Table 5 — Prism imbalance (relative prism error) tolerances for single-vision and multifocal lenses
Higher absolute Tolerance on the horizontal Tolerance on the vertical
ordered component prism value component component
(Relative to the ordered (Relative to the ordered
∆ centration distance) centration distance)
a a
For powers W 0,00 to u 3,25 D For powers W 0,00 to u 5,00 D
0,67 ∆ 0,50 ∆
W 0,00 to u 2,00
a a
For powers > 3,25 D For powers > 5,00 D
the prismatic effect of 2,0 mm the prismatic effect of 1,0 mm
displacement displacement
a a
For powers W 0,00 to u 3,25 D For powers W 0,00 to u 5,00 D
1,00 ∆ 0,75 ∆
> 2,00 to u 10,00
a a
For powers > 3,25 D For powers > 5,00 D
0,33 ∆ + the prismatic effect of 2,0 mm 0,25 ∆ + the prismatic effect of 1,0 mm
displacement displacement
a a
For powers W 0,00 to u 3,25 D For powers W 0,00 to u 5,00 D
1,25 ∆ 1,00 ∆
> 10,00
a a
For powers > 3,25 D For powers > 5,00 D
0,58 ∆ + the prismatic effect of 2,0 mm 0,50 ∆ + the prismatic effect of 1,0 mm
displacement displacement
a
These tolerances are applied to the lowest absolute principal power of the pair of lenses.

5.3.6 Prism imbalance (relative prism error
...