SIST EN ISO 9801:2000
(Main)Ophthalmic instruments - Trial case lenses (ISO 9801:1997)
Ophthalmic instruments - Trial case lenses (ISO 9801:1997)
Specification of tolerances of lenses for the determination of eye deficiency (ametropia) in order to achieve comparable test results
Ophthalmische Instrumente - Refraktionsgläser (ISO 9801:1997)
Diese Internationale Norm legt Anforderungen an gefaßte ophthalmische Refraktionsgläser mit voller oder reduzierter Öffnung fest, die zur Bestimmung der Fehlsichtigkeit des Auges dienen.
Instruments ophtalmiques - Verres de boîte d'essai (ISO 9801:1997)
Oftalmični instrumenti - Poskusne leče (ISO 9801:1997)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 9801:2000
01-januar-2000
2IWDOPLþQLLQVWUXPHQWL3RVNXVQHOHþH ,62
Ophthalmic instruments - Trial case lenses (ISO 9801:1997)
Ophthalmische Instrumente - Refraktionsgläser (ISO 9801:1997)
Instruments ophtalmiques - Verres de boîte d'essai (ISO 9801:1997)
Ta slovenski standard je istoveten z: EN ISO 9801:1999
ICS:
11.040.70 Oftalmološka oprema Ophthalmic equipment
SIST EN ISO 9801:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 9801:2000
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SIST EN ISO 9801:2000
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SIST EN ISO 9801:2000
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SIST EN ISO 9801:2000
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SIST EN ISO 9801:2000
IS0
INTERNATIONAL
STANDARD
9801
First edition
1997006- 15
Ophthalmic instruments - Trial case lenses
Instruments ophtalmiques - Verres de bofte d’essai
Reference number
IS0 9801:1997(E)
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SIST EN ISO 9801:2000
IS0 9801:1997(E)
Foreword
IS0 (the international Organization for Standardization) is a worldwide federation of national standards bodies (IS0
member bodies). The work of preparing International Standards is normally carried out through IS0 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. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees a .re circul ated to the member bodies for voting.
75 % of the me mber bodies casting a vote.
Publication as an I nternationa I Standard requires approval by at least
International Standard IS0 9801 was prepared by Technical Committee ISO/TC 172, Optics and optical
instruments, Subcommittee SC 7, Ophthalmic optics and instruments.
Annexes A, B and C of this International Standard are for information only.
0 IS0 1997
part of this publication may be reproduced or
All rights reserved. Unless otherwise specified, no utilized in any form or by any means, electronic
or mechanical, including photocopying and microfi Im, without permission in writing from the publ isher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
x.400 c=ch; a=4OOnet; p=iso; o=isocs; s=central
Printed in Switzerland
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SIST EN ISO 9801:2000
IS0 9801 :1997(E)
INTERNATIONAL STANDARD @ IS0
Trial case lenses
Ophthalmic instruments -
1 Scope
This International Standard specifies requirements for mounted ophthalmic full- and/or reduced-aperture trial case
lenses for the determination of the refractive error of the eye.
This International Standard takes priority over IS0 15004, if differences exist.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 7944:- l) , Optics and op tical instruments - Reference wavelengths.
2), Ophthalmic optics - Spectacle lenses - Vocabulary.
IS0 13666:-
IS0 15004:- 2), Ophthalmic instruments - Fundamental requirements and test methods.
3 Definitions
For the purposes of this International Standard, the definitions given in IS0 13666 and the following apply.
31
Gal case lens
lens, in a mount, which is used to assess the refractive error of the human eye
32
fkl-aperture trial case lens
trial case lens with a protective mount of maximal practical wall thickness of approximately 1 mm, allowing the
maximum available free lens aperture
33
riduced-aperture trial case lens
trial case lens with the designated free lens aperture significantly less than the mount outer diameter, allowing for
considerable reduction in lens thicknesses to be made
34
abditive power trial case lens set
train of spherical, cylindrical or spherocylindrical combination of trial case lenses, in which the measured back-
vertex power at the last surface equals the meridional sum of the labelled values of the train lenses when each
element is placed in its specified frame cell (see IS0 12867)
I) To be published. (Revision of IS0 7944:1984)
2, To be published.
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SIST EN ISO 9801:2000
@ IS0
IS0 9801:1997(E)
35
l&s power
(1) (spherical lens) back-vertex power, expressed in dioptres (D)
back-vertex power in the principal meridian not equal to zero, expressed in dioptres (D)
(2) (cylindrical lens)
NOTE -
Cylindrical trial case lenses have one principal meridian with zero power.
36
pknatic power
(prismatic lens, prism) prismatic effect, measured as the displacement, in centimetres, of the light ray in a plane
perpendicular to its line of incidence on the lens at a distance of 1 m
Prismatic power is expressed in prism dioptres (A).
NOTE 1
NOTE 2 The prism base is marked by a line or triangle on the mount (see clause 6). The position of the prism base is
indicated according to IS0 8429.
4 Requirements
4.1 General
The trial case lenses shall conform to the requirements specified in IS0 15004. Conformity to the requirements
specified in 4.2, 4.3 and 4.4 shall be verified as described in clause 5.
4.2 Optical requirements
The trial case lenses shall conform to the requirements specified in tables 1 to 6. Conformity to these requirements
shall be verified as described in 5.1.
The dioptric powers indicated in tables 1 to 4 shall be referenced to the wavelength a = 546,07 nm or alternatively
a = 587,56 nm according to IS0 7944.
If the requirements are not met for both wavelengths, the reference wavelength used shall be indicated.
The requirements for lenses with nominal zero power (plano) are given in table 1.
- Tolerances on lenses with zero power
Table 1
Tolerance on
mean power residual astigmatism prismatic power
Nominal
lens power
s1+s2
Is,-s2I
2
D D
D
A
0,03 0,06
0
+ 0,03
NOTE - S1 and S2 refer to the vertex powers in the principal meridians.
I
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SIST EN ISO 9801:2000
@ IS0 IS0 9801:1997(E)
The requirements for lenses with spherical power are given in table 2.
Table 2 - Tolerances on lenses with spherical power
mean power residual astigmatism
S, and Sz refer to the vertex powers in the principal meridians.
NOTE -
The requirements for lenses with cylindrical power are as follows:
a) The tolerances in the afocal principal meridian shall be + 0,03 D and 0,12 A.
b)
The tolerances on the cylindrical power principal meridian are given in table 3.
Table 3 - Tolerances on lenses with cylindrical power
Tolerance
Nominal cylindrical power
D
D
1
0,12
+ 0,03
I I
> 0,12 to I,00
+ 0,06
I I
> 1 ,oo to 4,00
+ 0,09
r-
I
> 4,00 to 6,00
+ 0,12
> 6,00
k 0,18
The requirements for lenses with prismatic power are given in table 4.
Table 4 - Tolerances on lenses with prismatic power
Prismatic power Tolerance
D
A
tolerance spherical astigmatic
nominal
~6 + 0,12 + 0,03 0,03
>6 k 0,25 + 0,03 0,03
3
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SIST EN ISO 9801:2000
@ IS0
IS0 9801:1997(E)
The accuracy of the optical centring of spherical and cylindrical lenses shall be as given in table 5.
Table 5 - Tolerances on centration
of the mount
> 8,00 to 12,00
+ 0,50
> 12,00
+ 0,75
The accuracy of the positions of the cylinder axis or prism base in relation to their corresponding marks (see
clause 6) shall be as given in table 6.
- Tolerances on marking of the cylinder axis and the prism base
Table 6
Nominal cylindrical power
Tolerance
D
I
s 0,25
t 3”
Lenses with cylindrical power
> 0,25 to 0,50
+ 2O
> 0,50
&I0
Nominal prismatic power
Tolerance
A
s 0,5
+ 7O
> 0,5 to 1 ,o
+ 4”
Lenses with prismatic power
> 1 ,o to 2,0
+ 2O
> 2,0 to IO,0
+ 1,5O
> IO,0
+ I”
4.3 Construction
The following requirements shall apply to all mounts and mounted lenses
4.3.1 Dimensions
A trial case lens shall have a circular mount, the rounded edges of which shall have a maximum radius of I,4 mm.
The outer diameter of the mounted lens shall be 38 -i 2 mm.
9
NOTE 1 For full- and reduced-aperture mounts in current use, the outer diameters of both mount types are equal.
The maximum thickness of the trial case lens including the mount shall not exceed 2,8 mm.
NOTE 2 Trial case lenses are intended to fit into a trial frame with a lens separation of 3 mm as specified in IS0 12867.
Full-aperture lenses with power in excess of + 5,00 D may exceed this thickness limit.
4
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SIST EN ISO 9801:2000
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