ISO/TR 11797:2024 PDF

Ophthalmic optics – Spectacle lenses – Power and prism measurements

Название (английский):

ISO/TR 11797:2024

Ophthalmic optics – Spectacle lenses – Power and prism measurements

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 50
Дата публикации:: 6 ноября 2024 г.
Издание:: ISO TR 11797 edition 1 version 1
ICS:: 11.040.70

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Описание (английский):

This document describes the methods currently used in applying tolerances to the focal powers of spectacle lenses and methods that can be considered for adoption in the future; it also describes methods of measuring the prism imbalance (relative prism error) between the lenses of a mounted pair. The results of a 2014 survey of manufacturing capability for lens power and a 2018 international web survey are discussed, as are possible new methods for applying tolerances to the focal power of spectacle lenses.

Технические детали

Технический комитет: ISO/TC 172/SC 7 - Ophthalmic optics and instruments
SKU: ISO/TR 11797:2024

Abstract

Overview - ISO/TR 11797:2024 (Ophthalmic optics - Spectacle lenses - Power and prism measurements)

ISO/TR 11797:2024 is a Technical Report from ISO/TC 172/SC 7 that surveys and documents current methods for applying tolerances to spectacle lens focal power and for measuring prism imbalance (relative prism error) between lenses in a mounted pair. The report describes existing measurement methodologies, discusses results from a 2014 manufacturing capability study and a 2018 international web survey, and considers potential new methods for power tolerance application and prism verification. This document is descriptive and intended to inform future revisions of related standards.

Key topics and technical requirements

Scope and purpose
- Describes methods currently used to verify spectacle lens power and prism, and considers methods for future adoption.
- Focuses on both uncut lenses and finished mounted eyewear.
Power measurement methodologies
- Compares two principal approaches:
  - Three-parameter method - verifies two principal meridian powers independently (meridian 1 and meridian 2) plus cylindrical power; applies tolerances to each meridian.
  - Two-parameter method - verifies one principal meridian (sphere meridian) and the cylinder magnitude; this effectively yields a different tolerance on the secondary meridian.
- Discusses impact of cylinder convention on verification outcomes and pass/fail results.
- Reviews alternative metrics such as mean sphere (spherical equivalent), astigmatic difference, and scalar / RMS power error.
- Proposes a tiered approach with optical classes for differing tolerance levels.
Prism measurement methodologies
- Details methods for measuring prism imbalance between mounted lenses, including reference point marking and positioning uncertainties.
- Considers position-specific lenses and power-variation lens types.
- Notes tolerance expressions both as fixed prism values for low powers and as Prentice-rule–style position-dependent values (example positioning offsets discussed: 2 mm horizontally, 1 mm vertically).
Supporting material
- Includes literature search, lab capability survey, global web survey results, worked examples (Annex A–F) and bibliography to support methodology assessment.

Practical applications and intended users

Who uses it
- Spectacle lens manufacturers and surfacing laboratories
- Optical quality assurance and test laboratories
- Eyewear assemblers and finishing labs (verification of mounted eyewear)
- Standards committees, regulators, and conformity assessment bodies
- Optometrists and dispensing opticians involved in technical specification and complaint investigation
How it’s used
- To harmonize measurement practice and reduce trade barriers caused by inconsistent national tolerances.
- To inform quality control procedures for lens power and prism verification.
- To guide selection of measurement methodology (two‑ vs three‑parameter) appropriate to product type and manufacturing capability.

Related standards

ISO 21987 (verification of mounted spectacle lenses)
ISO 8980-1, ISO 8980-2 (spectacle lens tolerances and test methods)
ISO 13666 (ophthalmic optics vocabulary)

ISO/TR 11797:2024 is a practical reference for organizations seeking to understand current industry practice and the technical implications of different power and prism verification methods.

Overview - ISO/TR 11797:2024 (Ophthalmic optics - Spectacle lenses - Power and prism measurements)

Key topics and technical requirements

Scope and purpose
- Describes methods currently used to verify spectacle lens power and prism, and considers methods for future adoption.
- Focuses on both uncut lenses and finished mounted eyewear.
Power measurement methodologies
- Compares two principal approaches:
  - Three-parameter method - verifies two principal meridian powers independently (meridian 1 and meridian 2) plus cylindrical power; applies tolerances to each meridian.
  - Two-parameter method - verifies one principal meridian (sphere meridian) and the cylinder magnitude; this effectively yields a different tolerance on the secondary meridian.
- Discusses impact of cylinder convention on verification outcomes and pass/fail results.
- Reviews alternative metrics such as mean sphere (spherical equivalent), astigmatic difference, and scalar / RMS power error.
- Proposes a tiered approach with optical classes for differing tolerance levels.
Prism measurement methodologies
- Details methods for measuring prism imbalance between mounted lenses, including reference point marking and positioning uncertainties.
- Considers position-specific lenses and power-variation lens types.
- Notes tolerance expressions both as fixed prism values for low powers and as Prentice-rule–style position-dependent values (example positioning offsets discussed: 2 mm horizontally, 1 mm vertically).
Supporting material
- Includes literature search, lab capability survey, global web survey results, worked examples (Annex A–F) and bibliography to support methodology assessment.

Practical applications and intended users

Who uses it
- Spectacle lens manufacturers and surfacing laboratories
- Optical quality assurance and test laboratories
- Eyewear assemblers and finishing labs (verification of mounted eyewear)
- Standards committees, regulators, and conformity assessment bodies
- Optometrists and dispensing opticians involved in technical specification and complaint investigation
How it’s used
- To harmonize measurement practice and reduce trade barriers caused by inconsistent national tolerances.
- To inform quality control procedures for lens power and prism verification.
- To guide selection of measurement methodology (two‑ vs three‑parameter) appropriate to product type and manufacturing capability.

Related standards

ISO 21987 (verification of mounted spectacle lenses)
ISO 8980-1, ISO 8980-2 (spectacle lens tolerances and test methods)
ISO 13666 (ophthalmic optics vocabulary)

ISO/TR 11797:2024 is a practical reference for organizations seeking to understand current industry practice and the technical implications of different power and prism verification methods.

ISO/TR 11797:2024 PDF

Технические детали

Abstract

Overview - ISO/TR 11797:2024 (Ophthalmic optics - Spectacle lenses - Power and prism measurements)

Key topics and technical requirements

Practical applications and intended users

Related standards

Похожие стандарты

Abstract

Overview - ISO/TR 11797:2024 (Ophthalmic optics - Spectacle lenses - Power and prism measurements)

Key topics and technical requirements

Practical applications and intended users

Related standards

Похожие стандарты

Ophthalmic optics - Mounted spectacle lenses (ISO 21987:2017)

Ophthalmic optics - Uncut finished spectacle lenses - Part 1: Specifications for single-vision and multifocal…

Ophthalmic optics - Uncut finished spectacle lenses - Part 2: Specifications for power-variation lenses (ISO…

Ophthalmic optics - Spectacle lenses - Vocabulary (ISO 13666:2019)