EN ISO 9337-2:2004
(Main)Contact lenses - Determination of back vertex power - Part 2: Measurement of contact lenses immersed in saline (ISO 9337-2:2004)
Contact lenses - Determination of back vertex power - Part 2: Measurement of contact lenses immersed in saline (ISO 9337-2:2004)
Kontaktlinsen - Bestimmung des bildseitigen Scheitelbrechwertes - Teil 2: Kontaktlinsenmessung in Immersion (Kochsalzlösung) (ISO 9337-2:2004)
Dieser Teil von ISO 9337 beschreibt Prüfverfahren für die Bestimmung des bildseitigen Scheitelbrechwertes von weichen Kontaktlinsen in Immersion in Kochsalzlösung. Sie gilt für verkaufsfertige Kontaktlinsen (Endprodukte).
Lentilles de contact - Détermination de la puissance frontale arrière - Partie 2: Mesurage des lentilles de contact immergées dans une solution saline (ISO 9337-2:2004)
Contact lenses - Determination of back vertex power - Part 2: Measurement of contact lenses immersed in saline (ISO 9337-2:2004)
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Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2005
Contact lenses - Determination of back vertex power - Part 2: Measurement of
contact lenses immersed in saline (ISO 9337-2:2004)
Contact lenses - Determination of back vertex power - Part 2: Measurement of contact
lenses immersed in saline (ISO 9337-2:2004)
Kontaktlinsen - Bestimmung des bildseitigen Scheitelbrechwertes - Teil 2:
Kontaktlinsenmessung in Immersion (Kochsalzlösung) (ISO 9337-2:2004)
Lentilles de contact - Détermination de la puissance frontale arriere - Partie 2: Mesurage
des lentilles de contact immergées dans une solution saline (ISO 9337-2:2004)
Ta slovenski standard je istoveten z: EN ISO 9337-2:2004
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 9337-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2004
ICS 11.040.70
English version
Contact lenses - Determination of back vertex power - Part 2:
Measurement of contact lenses immersed in saline (ISO 9337-
2:2004)
Lentilles de contact - Détermination de la puissance Kontaktlinsen - Bestimmung des bildseitigen
frontale arrière - Partie 2: Mesurage des lentilles de contact Scheitelbrechwertes - Teil 2: Kontaktlinsenmessung in
immergées dans une solution saline (ISO 9337-2:2004) Immersion (Kochsalzlösung) (ISO 9337-2:2004)
This European Standard was approved by CEN on 15 June 2004.
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.
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© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9337-2:2004: E
worldwide for CEN national Members.
Foreword
This document (EN ISO 9337-2:2004) 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 January 2005, and conflicting national
standards shall be withdrawn at the latest by January 2005.
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 9337-2:2004 has been approved by CEN as EN ISO 9337-2:2004 without any
modifications.
INTERNATIONAL ISO
STANDARD 9337-2
First edition
2004-07-15
Contact lenses — Determination of back
vertex power —
Part 2:
Measurement of contact lenses immersed
in saline
Lentilles de contact — Détermination de la puissance frontale arrière —
Partie 2: Mesurage des lentilles de contact immergées dans une
solution saline
Reference number
ISO 9337-2:2004(E)
©
ISO 2004
ISO 9337-2:2004(E)
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ii © ISO 2004 – All rights reserved
ISO 9337-2:2004(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
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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
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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 9337-2 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 7,
Ophthalmic optics and instruments.
ISO 9337 consists of the following parts, under the general title Contact lenses — Determination of back
vertex power:
Part 1: Method using focimeter with manual focusing
Part 2: Measurement of contact lenses immersed in saline
ISO 9337-2:2004(E)
Introduction
It is intended that the test methods described in this part of ISO 9337 should be used by contact lens
manufacturers, practitioners and other interested parties.
It has been assumed in drafting this part of ISO 9337 that the execution of its provisions will be entrusted to
appropriately qualified and experienced people.
iv © ISO 2004 – All rights reserved
INTERNATIONAL STANDARD ISO 9337-2:2004(E)
Contact lenses — Determination of back vertex power —
Part 2:
Measurement of contact lenses immersed in saline
1 Scope
This part of ISO 9337 describes test methods for the determination of back vertex power of soft contact lenses
immersed in saline. It is applicable to finished contact lenses.
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 8320-1, Contact lenses and contact lens care products — Vocabulary — Part 1: Contact lenses
ISO 8320-2, Contact lenses and contact lens care products — Vocabulary — Part 2: Contact lens care
products
ISO 10344, Optics and optical instruments — Contact lenses — Saline solution for contact lens testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8320-1 and ISO 8320-2 apply.
4 Test methods
The test methods specified in Annex A are listed in Table 1, together with a statement of their reproducibility
when applied to spherical or toric soft contact lenses. Reproducibility of a method should be half or less of the
product tolerance in order to verify the tolerance.
ISO 9337-2:2004(E)
Table 1 — Test methods
Test method Application Reproducibility, R
Spherical soft lenses 0,252 8 D
Toric soft lenses:
Moiré deflectometer
Sphere power 0,442 1 D
Cylinder power 0,260 4 D
Axis direction 3,416°
Spherical soft lenses 0,070 8 D
Toric soft lenses:
Hartmann method
Sphere power 0,181 7 D
Cylinder power 0,243 9 D
Axis direction 5,644 8°
2 © ISO 2004 – All rights reserved
ISO 9337-2:2004(E)
Annex A
(normative)
Determination of back vertex power of contact lenses immersed in saline
A.1 Scope
This annex specifies a method for determining the back vertex power of soft contact lenses immersed in
saline using: (1) the Moiré deflectometer and (2) the Hartmann method.
A.2 Principle
The Moiré deflectometer is a quantitative instrument for mapping ray deflections of a beam passed through
or reflected off a test object. The technique is based on the Moiré effect, a phenomenon that causes a fringe
pattern to appear when two gratings are placed at a small angle to each other. The fringe pattern is detected
by a CCD camera and digitized. Digital information relating to the fringe pattern is relayed through the electro-
optical interface to the control software for analysis. The resulting image is displayed on a visual display unit.
The system is calibrated so that when there is no contact lens in the cuvette, the beam is collimated and
straight vertical fringes are observed. When a contact lens is inserted in the cuvette, the fringes deviate from
the vertical. The laser light source is translated by means of a servomotor under software control until the
fringes are restored to the vertical. The power of the cuvette-contact lens combination is determined from the
distance the laser travels, from which the dioptric power of the lens being measured is calculated. It is
necessary to calculate the back vertex power of the contact lens in air based on the parameters of the cuvette,
saline and contact lens.
The Hartmann instrument is used to measure the power-related components of optical elements that are
placed in the path of a beam of light that then passes through a screen containing a number of microlenses.
Typically, the screen consists of an array of microlenses arranged in a square matrix. The measuring system
is arranged so that a reference image is taken before the optical element to be measured is placed in the
system. The image produced by the microlenses is memorized; this acts as the reference image. The optical
element to be measured is then introduced to the system. The image of the microlenses is altered by the
power-related parameters of the element being measured. It can be shown that the transverse aberrations of
the image of the microlenses are a function of the power-related parameters of the element being measured.
An algorithm is used to calculate the power-related parameters of the element being measured.
A.3 Apparatus and reagent
A.3.1 Moiré deflectometer or Hartmann instrument, having the following capabilities:
A.3.1.1 The diameter of the central aperture through which the power is measured shall be adjustable
and at least be capable of being set to 4,50 mm ± 0,50 mm.
A.3.1.2 The instrument shall have a measuring range of at least − 25,00 D to + 25,00 D.
NOTE This requirement should apply to the powers in air; suitable allowance should be made in the system for the
power of lenses immersed in saline.
A.3.1.3 The instrument shall have a positioning mechanism for the cuvettes containing the contact
lenses, designed so that the lens being measured is located centrally in the measuring system.
ISO 9337-2:2004(E)
A.3.2 Eight spherical test lenses, with the nominal back vertex power of each test lens being within one
dioptre of − 20,00 D, − 15,00 D, − 10,00 D, − 5,00 D, + 5,00 D, + 10,00 D, + 15,00 D and + 20,00 D. The
powers of the test lenses shall be traceable to a national or International Standard. The following parameters
shall be known for each of the test lenses, to the accuracy given:
centre thickness to ± 0,01 mm;
base curve to ± 0,05 mm;
diameter to ± 0,05 mm;
refractive index correct to 3 places of decimals.
NOTE Test lenses conforming to ISO 9342-2 may be used.
A.3.3 Calibrated cuvettes, such that the optical properties of the cell walls of the cuvettes used in the
measurement shall not influence the outcome of the test.
A.3.4 Standard saline solution conforming to ISO 10344. The refractive index of the saline solution shall
be known correct to 3 places of decimals.
A.4 Procedure
A.4.1 Conditioning of lenses prior to testing
Condition each test lens prior to testing as follows.
Immerse in a vial filled with standard saline solution (A.3.4) and maintain at a temperature of 20 °C ± 0,5 °
...
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