SIST EN ISO 18369-1:2006
(Main)Ophthalmic optics - Contact lenses - Part 1: Vocabulary, classification system and recommendations for labelling specifications (ISO 18369-1:2006)
Ophthalmic optics - Contact lenses - Part 1: Vocabulary, classification system and recommendations for labelling specifications (ISO 18369-1:2006)
This part of ISO 18369 identifies and defines the terms applicable to the physical, chemical and optical properties of contact lenses, their manufacture and uses. It provides a vocabulary of terms and, when appropriate, the international symbol and abbreviation associated with a specific term. This part of ISO 18369 also defines the terms relating to contact lens care products. It also incorporates the classifications of contact lens materials and gives recommendations for the labelling of the specifications of contact lenses.
Augenoptik - Kontaktlinsen - Teil 1: Begriffe, Einteilung von Kontaktlinsenmaterialien und Empfehlungen für die Schreibweise von Kontaktlinsenspezifikationen (ISO 18369-1:2006)
Dieser Teil von ISO 18369 legt Begriffe für die physikalischen, chemischen und optischen Eigenschaften von Kontaktlinsen sowie deren Herstellung und Gebrauch fest. Er gibt hierzu die Begriffe und ihre Definitionen so¬wie, wo zutreffend, die international festgelegten Symbole und Kurzzeichen an. Dieser Teil von ISO 18369 legt weiterhin Begriffe für Kontaktlinsenpflegemittel fest. Darüber hinaus legt er ein System zur Einteilung von Kontakt¬linsen¬materialien fest, und er empfiehlt Schreibweisen für die Angabe von Kontaktlinsen¬spezifika¬tio¬nen.
Optique ophtalmique - Lentilles de contact - Partie 1: Vocabulaire, systeme de classification et recommandations pour l'étiquetage des spécifications (ISO 18369-1:2006)
L'ISO 18369-1:2006 définit les termes applicables aux propriétés physiques, chimiques et optiques des lentilles de contact, à leur fabrication et à leur utilisation. Elle fournit une liste de termes et, si nécessaire, le symbole et l'abréviation associés à un terme spécifique. L'ISO 18369-1:2006 définit également les termes relatifs aux produits d'entretien des lentilles de contact. Elle comporte en outre la classification des matériaux de lentilles de contact et donne les recommandations pour les spécifications d'étiquetage des lentilles de contact.
Očesna optika - Kontaktne leče - 1. del: Slovar, sistem razvrstitve in priporočila za označevanje specifikacij (ISO 18369-1:2006)
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Ophthalmic optics - Contact lenses - Part 1: Vocabulary, classification system and recommendations for labelling specifications (ISO 18369-1:2006)Optique ophtalmique - Lentilles de contact - Partie 1: Vocabulaire, systeme de classification et recommandations pour l'étiquetage des spécifications (ISO 18369-1:2006)Augenoptik - Kontaktlinsen - Teil 1: Begriffe, Einteilung von Kontaktlinsenmaterialien und Empfehlungen für die Schreibweise von Kontaktlinsenspezifikationen (ISO 18369-1:2006)Ta slovenski standard je istoveten z:EN ISO 18369-1:2006SIST EN ISO 18369-1:2006en,fr,de11.040.70Oftalmološka opremaOphthalmic equipment01.040.11Zdravstveno varstvo (Slovarji)Health care technology (Vocabularies)ICS:SIST EN ISO 8321-1:2002SIST EN ISO 8321-2:2000SIST EN ISO 8320-2:2002SIST EN ISO 11539:2001SIST EN ISO 8320-1:20031DGRPHãþDSLOVENSKI
STANDARDSIST EN ISO 18369-1:200601-december-2006
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN ISO 18369-1
August 2006 ICS 01.040.11; 11.040.70 Supersedes
EN ISO 8320-1:2003,
EN ISO 8320-2:2001and EN ISO 11539:1999, and partly supersedes EN ISO 8321-1:2002 andEN ISO 8321-2:2000English Version
Ophthalmic optics - Contact lenses - Part 1: Vocabulary, classification system and recommendations for labelling specifications (ISO 18369-1:2006)
Optique ophtalmique - Lentilles de contact - Partie 1: Vocabulaire, système de classification et recommandations pour l'étiquetage des spécifications (ISO 18369-1:2006)
Augenoptik - Kontaktlinsen - Teil 1: Begriffe, Einteilung von Kontaktlinsenmaterialien und Empfehlungen für die Schreibweise von Kontaktlinsenspezifikationen (ISO 18369-1:2006) This European Standard was approved by CEN on 19 May 2006.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36
B-1050 Brussels © 2006 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 18369-1:2006: E
EN ISO 18369-1:2006 (E)
2
Foreword
This document (EN ISO 18369-1:2006) 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 February 2007, and conflicting national standards shall be withdrawn at the latest by February 2007.
This document supersedes EN ISO 8320-1:2003, EN ISO 8320-2:2001 and EN ISO 11539:1999 and partly supersedes EN ISO 8321-1:2002 and EN ISO 8321-2:2000.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Endorsement notice
The text of ISO 18369-1:2006 has been approved by CEN as EN ISO 18369-1:2006 without any modifications.
NOTE: A-Deviations are given in Annex ZA (informative)
EN ISO 18369-1:2006 (E)
3 ANNEX ZA
(informative) A-deviations
A-deviation: National deviation due to regulations, the alteration of which is for the time being outside the competence of the CEN/CENELEC member.
This European Standard does not fall under any Directive of the EC. In the relevant CEN/CENELEC countries these A-deviations are valid instead of the provisions of the European Standard until they have been removed.
The legislative situation in Germany requires the unit "dioptre" be designated by the symbol "dpt" instead of "D".
This is to avoid conflict with the rules of ISO 1000 being the basic International Standard on symbols and units and with the respective basic resolution of the CGPM (International Conference on Weights and Mesures).
Identification of the regulation:
Gesetz über die Einheiten im Messwesen vom 02.07.1969 in der Fassung der Bekanntmachung vom 22.04.1985;
and
Ausführungsverordnung zum Gesetz über Einheiten im Messwesen (Einheitenverordnung - EinhV) vom 13.12.1985, § 1 und Anlage 1, Nr. 9.
Reference numberISO 18369-1:2006(E)© ISO 2006
INTERNATIONAL STANDARD
ISO18369-1First edition2006-08-15Ophthalmic optics — Contact lenses — Part 1: Vocabulary, classification system and recommendations for labelling specifications Optique ophtalmique — Lentilles de contact — Partie 1: Vocabulaire, système de classification et recommandations pour l'étiquetage des spécifications
ISO 18369-1:2006(E) ©
ISO 2006 The reproduction of the terms and definitions contained in this International Standard is permitted in teaching manuals, instruction booklets, technical publications and journals for strictly educational or implementation purposes. The conditions for such reproduction are: that no modifications are made to the terms and definitions; that such reproduction is not permitted for dictionaries or similar publications offered for sale; and that this International Standard is referenced as the source document. With the sole exceptions noted above, no other part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 • CH-1211 Geneva 20 Tel.
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ISO 18369-1:2006(E) © ISO 2006 – All rights reserved
iiiContents Page Foreword.iv Introduction.v 1 Scope.1 2 Terms, definitions and symbols.1 2.1 Terms and definitions.1 2.1.1 Basic terms.1 2.1.2 Contact lens parameters and design.3 2.1.3 Aspheric contact lenses.15 2.1.4 Bifocal and multifocal contact lenses.16 2.1.5 Scleral contact lenses and shells.18 2.1.6 Contact lens material properties.20 2.1.7 Tinted contact lenses.23 2.1.8 Contact lens manufacture.23 2.1.9 Packaging and labelling of contact lenses and contact lens care products.23 2.1.10 Contact lens usage and wear modality.25 2.1.11 Contact lens hygienic management and contact lens care products.26 2.1.12 Miscellaneous.29 2.2 Symbols.31 3 Classification of contact lens materials.32 Annex A (informative)
Specification of rigid contact lenses.35 Annex B (informative)
Specification of soft contact lenses.43 Bibliography.45 Alphabetical index.46
ISO 18369-1:2006(E) iv
© ISO 2006 – All rights reserved 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 18369-1 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 7, Ophthalmic optics and instruments. This first edition cancels and replaces ISO 8320-1:2003, ISO 8320-2:2001 and ISO 11539:1999, which have been technically revised. Furthermore, together with ISO 18369-2, it cancels and replaces ISO 8321-1:2002 and ISO 8321-2:2000, which have been technically revised. ISO 18369 consists of the following parts, under the general title Ophthalmic optics — Contact lenses: =Part 1: Vocabulary, classification system and recommendations for labelling specifications =Part 2: Tolerances =Part 3: Measurement methods =Part 4: Physicochemical properties of contact lens materials
ISO 18369-1:2006(E) © ISO 2006 – All rights reserved
vIntroduction The ISO 18369 series applies to contact lenses, which are devices worn over the front surface of the eye in contact with the preocular tear film. This part of ISO 18369 covers rigid (hard) corneal and scleral contact lenses, as well as soft contact lenses. Rigid lenses maintain their own shape unsupported and are made of transparent optical-grade plastics, such as polymethylmethacrylate (PMMA), cellulose acetate butyrate (CAB), polyacrylate/siloxane copolymers, rigid polysiloxanes (silicone resins), butylstyrenes, fluoropolymers, and fluorosiloxanes, etc. Soft contact lenses are easily deformable and require support for proper shape. A very large subset of soft contact lenses consists of transparent hydrogels containing water in concentrations greater than 10 %. Soft contact lenses can also be made of non-hydrogel materials, e.g. flexible polysiloxanes (silicone elastomers). The ISO 18369 series is applicable to determining allowable tolerances of parameters and properties important for proper functioning of contact lenses as optical devices. The ISO 18369 series includes tolerances for single vision contact lenses, bifocal lenses, lenses that alter the flux density and/or spectral composition of transmitted visible light (tinted or pigmented contact lenses, such as those with enhancing, handling, and/or opaque tints), and lenses that significantly attenuate ultraviolet radiation (UVR absorbing lenses). The ISO 18369 series covers contact lenses designed with spherical, toric, and aspheric surfaces, and recommended methods for the specification of contact lenses. The vocabulary portion (2.1) of this part of ISO 18369 contains the terms and definitions primarily used in the contact lens field. A list of terms having special symbols is given in Table 1. The list of terms and definitions does not include all ISO terms, definitions, and symbols used in the contact lens field. It is intended to be a convenient reference source from which the contents have been compiled from the text of this and other ISO standards applicable to the manufacture, evaluation, measurement, labelling and marketing of contact lenses and contact lens care products. An alphabetical index was added for rapid finding of terms. Words are grouped under several topics by reference number according to the general category into which each word logically fitted. The preferred form of each term is listed on the first line after its reference number. Other admitted forms have been placed on subsequent lines after the preferred form. All admitted terms are given in bold-faced type. A few obsolete and superseded terms are listed for historical reference and convenience and as an aid to comprehension but are indicated as deprecated and are no longer to be used. Obsolete and superseded terms are not in bold-faced type so that they may be clearly identified as terms used historically. Figure 1 gives a schema of the classification and provides examples. It does not take into account all possible characteristics (hence resulting qualifiers) used in contact lens designation. Combinations of more than one qualifier are often used in contact lens designation.
ISO 18369-1:2006(E) vi
© ISO 2006 – All rights reserved
Figure 1 — Classification of contact lenses according to various characteristics
leads to various qualifiers used in their designation
INTERNATIONAL STANDARD ISO 18369-1:2006(E) © ISO 2006 – All rights reserved
1Ophthalmic optics — Contact lenses — Part 1: Vocabulary, classification system and recommendations for labelling specifications 1 Scope This part of ISO 18369 identifies and defines the terms applicable to the physical, chemical and optical properties of contact lenses, their manufacture and uses. It provides a vocabulary of terms and, when appropriate, the international symbol and abbreviation associated with a specific term. This part of ISO 18369 also defines the terms relating to contact lens care products. It also incorporates the classifications of contact lens materials and gives recommendations for the labelling of the specifications of contact lenses. 2 Terms, definitions and symbols 2.1 Terms and definitions 2.1.1 Basic terms 2.1.1.1 contact lens any ophthalmic lens designed to be worn on the front surface of the eye NOTE This term includes contact lenses of plano power. 2.1.1.2 corneal contact lens contact lens having a total diameter less than the visible iris diameter and designed to be worn in its entirety on the cornea 2.1.1.3 scleral contact lens contact lens designed to be worn in front of the cornea and on the adjacent portion of the surrounding bulbar conjunctiva NOTE See 2.1.5 for specific terms concerning scleral contact lenses. 2.1.1.4 lenticular contact lens contact lens having a front optic zone made smaller than the total diameter NOTE This construction is conventionally used to reduce the centre thickness of a positive power contact lens or reduce the edge thickness of a negative power contact lens. 2.1.1.5 contact shell contact lens not designed to correct vision
ISO 18369-1:2006(E) 2
© ISO 2006 – All rights reserved 2.1.1.6 scleral shell rigid contact shell with a scleral zone NOTE See 2.1.5 for specific terms concerning scleral shells. 2.1.1.7 rigid contact lens hard contact lens contact lens which, in its final form and under normal conditions, retains its form without support 2.1.1.8 rigid gas-permeable contact lens RGP contact lens hard gas-permeable contact lens (deprecated) rigid contact lens which contains one or more components in the contact lens polymer in sufficient concentration to permit oxygen transmission through the contact lens 2.1.1.9 soft contact lens contact lens which requires support to maintain its form 2.1.1.10 hydrogel contact lens hydrophilic contact lens (deprecated) contact lens made of water-absorbing material having equilibrium water content greater than or equal to 10 % in standard saline solution at 20 °C NOTE Standard saline solution is prepared as specified in ISO 18369-3. 2.1.1.11 composite contact lens contact lens composed of two or more different materials EXAMPLES Laminated lens, a fused segment lens, or a lens with a rigid centre and a flexible periphery. 2.1.1.12 surface treated contact lens contact lens whose surfaces have been modified to make the surface characteristics different to those of the bulk material 2.1.1.13 bifocal contact lens multifocal contact lens having two optic zones, usually for distance and near-vision correction NOTE See 2.1.4 for specific terms concerning bifocal contact lenses. 2.1.1.14 multifocal contact lens contact lens designed to provide two or more zones of different corrective powers NOTE See 2.1.4 for specific terms concerning multifocal contact lenses. 2.1.1.15 progressive power contact lens varifocal power contact lens contact lens designed to provide correction for more than one viewing range in which the power changes continuously, rather than discretely, over a part or the whole of the lens NOTE See 2.1.4 for specific terms concerning progressive power contact lenses.
ISO 18369-1:2006(E) © ISO 2006 – All rights reserved
32.1.1.16 contact lens accessory article intended specifically by its manufacturer to be used with a contact lens to enable the lens to be used in accordance with its intended purpose NOTE This term includes all devices recommended for use in the hygienic management of contact lenses, for hydrating contact lenses, or alleviating discomfort of contact lens wear by physical means. 2.1.1.17 contact lens care product contact lens accessory intended for use in maintaining the safety and performance of a contact lens after opening and removal of the lens from its primary container NOTE See 2.1.9 and 2.1.11 for specific terms concerning contact lens care products and the hygienic management of contact lenses. 2.1.1.18 other accessory for contact lenses item used for handling contact lenses or as a part of a contact lens care regimen excluding contact lens care products EXAMPLE Suction cup used to aid in the insertion of a contact lens onto or removal from the surface of the eye. NOTE This definition does not include the primary packaging (e.g. vials, blister packs or mailers) intended by the manufacturer to be used only for shipment of the contact lenses. 2.1.1.19 suction cup hand-held device designed with a small concave flexible tip intended to aid the insertion of a contact lens onto or removal from the eye by means of suction NOTE A suction cup is designed primarily for use with rigid corneal contact lenses. 2.1.1.20 contact lens container storage container contact lens case storage case container in which contact lenses are stored either dry or in a suitable solution by the user after removal from the primary container or the eye 2.1.2 Contact lens parameters and design 2.1.2.1 General terms 2.1.2.1.1 front vertex power Fv reciprocal of the paraxial front vertex focal length [ISO 13666:1998] NOTE The front vertex power is expressed in dioptres. 2.1.2.1.2 back vertex power F′v reciprocal of the paraxial back vertex focal length [ISO 13666:1998] NOTE The back vertex power is expressed in dioptres.
ISO 18369-1:2006(E) 4
© ISO 2006 – All rights reserved 2.1.2.1.3 positive power contact lens plus-power contact lens contact lens which causes parallel incident light (incident on a single optic zone) to converge to a real focus 2.1.2.1.4 negative power contact lens minus-power contact lens contact lens which causes parallel light (incident on a single optic zone) to diverge from a virtual focus 2.1.2.1.5 plano contact lens afocal contact lens contact lens whose back vertex power is zero 2.1.2.1.6 liquid lens fluid lens tear lens lacrimal lens refractive element formed by the liquid between the back optic zone of the contact lens and the cornea NOTE The liquid element of this lens is typically composed of tear fluid. 2.1.2.1.7 optic zone that part of a contact lens which has a prescribed optical effect NOTE The term may be qualified by either the prefix “back” or “front” in the case of a surface with a single optical component. In the case of an alternating image translating bifocal contact lens, the term may be qualified by either the prefix “distance” or “near”. In the case of a concentric multifocal contact lens, the term may be qualified by the prefix “central” or “peripheral”. 2.1.2.1.8 peripheral zone region with no prescribed refractive effect, of specified dimensions, surrounding the optic zone(s) NOTE There can be more than one peripheral zone. 2.1.2.1.9 displacement of optic d 〈non-scleral lenses〉 displacement of the optic zone relative to the lens periphery NOTE This term does not apply to scleral contact lenses. 2.1.2.1.10 geometric centre C centre of the circle containing the contact lens edge NOTE For a scleral contact lens, the geometric centre is taken as the centre of the optic zone. For a truncated contact lens, the geometric centre is taken as the centre of the circle that contains the circular portion of the edge. 2.1.2.1.11
optical decentration positioning of the optical centre at a point other than the geometric centre of the optic zone or central optic zone 2.1.2.1.12 contact lens axis line passing through the geometric centre, perpendicular to a plane containing the edge of a contact lens See Figure 2.
ISO 18369-1:2006(E) © ISO 2006 – All rights reserved
52.1.2.1.13 back vertex point on the posterior contact lens surface lying on the contact lens axis See Figure 2. 2.1.2.1.14 vertex sphere imaginary spherical surface touching the back vertex NOTE The radius of curvature of the vertex sphere is the same as the steepest back optic zone radius, back central optic radius, or back vertex radius of an aspheric lens (see Figure 2).
Key 1 contact lens axis 2 centre of vertex sphere 3 back vertex 4 vertex sphere 5 peripheral junction thickness, tPJ0 6 overall posterior sagitta Figure 2 — Schematic representation of a tri-curve contact lens including symbols of the main parameters describing its back surface 2.1.2.1.15 sagitta sagittal depth sagittal height maximum distance from a chord, which is perpendicular to the axis of rotation of a surface, to the curved surface
ISO 18369-1:2006(E) 6
© ISO 2006 – All rights reserved 2.1.2.1.15.1 overall posterior sagitta distance along the contact lens axis from the back vertex to a plane containing the contact lens edge See Figure 2. 2.1.2.1.16 edge that part of a contact lens which is contiguous with the front and back surfaces 2.1.2.1.17 edge form edge profile profile of the edge in a plane containing the contact lens axis 2.1.2.1.18 bevel narrow back peripheral zone, of a single spherical or aspherical curvature, adjacent to the edge of a contact lens 2.1.2.1.19 radial lift lR distance between a specified point on the back surface of a contact lens and the vertex sphere measured along a radius of curvature of the latter See Figure 3.
Key 1 front surface of contact lens 2 back surface of contact lens 3 vertex sphere 4 centre of vertex sphere 5 junction 6 specified point on the back surface of the contact lens; for radial and axial edge lift, specified point at the edge of the contact lens 7 axial lift, lA 8 radial lift, lR
Figure 3 — The difference between radial and axial lift 2.1.2.1.20 radial edge lift lER distance between a point on the back surface of a contact lens at the edge and the vertex sphere measured along the radius of curvature of the latter See Figure 3. NOTE This is often a value computed by the manufacturer and may be altered by the edging process.
ISO 18369-1:2006(E) © ISO 2006 – All rights reserved
72.1.2.1.21 axial lift lA distance between a specified point on the back surface and the vertex sphere measured parallel to the contact lens axis See Figure 3. 2.1.2.1.22 axial edge lift lEA distance between a point on the back of a contact lens at the edge and the vertex sphere, measured parallel to the contact lens axis See Figure 3. NOTE This is often a value computed by the manufacturer and may be altered by the edging process. 2.1.2.1.23 spherical surface 〈non-aspheric〉 surface described by rotating a circle about a line containing its centre 2.1.2.1.24 spherical surface 〈non-toric〉 surface having the same radius of curvature for meridians in all directions 2.1.2.1.25 sagittal radius of curvature radius of curvature in the sagittal plane at a specified off-axis point on the surface NOTE 1 The radius at a specified point on the surface is equal to the distance along the normal at that point to its intersection with the axis of rotation. NOTE 2 The sagittal plane contains the normal to the surface at the specified point, but does not contain the axis of rotation, being perpendicular to the tangential plane. 2.1.2.1.26 tangential radius of curvature radius of curvature in the tangential plane at a specified off-axis point on a surface NOTE The tangential plane contains both the normal to the surface at the point specified and the axis of rotation. 2.1.2.1.27 bi-curve contact lens contact lens whose back surface is composed of two intersecting spherical zones 2.1.2.1.28 tri-curve contact lens contact lens whose back surface is composed of three intersecting coaxial spherical zones 2.1.2.1.29 multi-curve contact lens contact lens with a back surface that is composed of more than three intersecting spherical zones 2.1.2.1.30 aspheric contact lens contact lens with its front or back optic zone of aspheric form NOTE See 2.1.3 for specific terms concerning aspheric contact lenses. 2.1.2.1.31 toric contact lens contact lens with front and/or back optic zone of toroidal form
ISO 18369-1:2006(E) 8
© ISO 2006 – All rights reserved 2.1.2.1.32 bi-toric contact lens contact lens having both front and back optic zones of toroidal form 2.1.2.1.33 toroidal zone zone having a surface with its maximum and minimum radii of curvature perpendicular to each other 2.1.2.1.34 toric periphery contact lens contact lens with one or more back peripheral zones of toroidal form that surround a spherical back optic zone 2.1.2.1.35 junction intersection of two adjacent zones NOTE This applies to both back and front surfaces. 2.1.2.1.36 tangential junction junction where the curvatures of adjacent zones have a common tangent See Figure 4. 2.1.2.1.37 transition transition zone junction which has been modified to smooth the change between adjacent curvatures See Figure 5. 2.1.2.1.38 blend polished, smoothed junction or transition zone between two different adjacent surface curvatures, typically applied at the junction (transition) between posterior zones cf. transition (2.1.2.1.37) NOTE This does not constitute the formation of an aspheric zone. 2.1.2.1.39 ballast rotationally asymmetrica
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