Overview
EN ISO 8598-1:2014 - Optics and optical instruments - Focimeters - Part 1: General purpose instruments defines requirements and test methods for general-purpose focimeters used to measure spectacle and contact lenses. It covers instruments that measure vertex power, cylinder axis, prismatic power and prism base setting within a restricted area of a lens (excluding instruments that measure the whole lens at once). The standard supports the ophthalmic community by providing methods to demonstrate conformity of spectacle lens products with existing international lens standards.
Key topics and technical requirements
- Scope and definitions: clear terminology for focimeter types (manual focusing, automated, continuously indicating, digitally rounding) and measurement concepts (indication, indication error, centration error, lens support, near portion power).
- Technical and metrological requirements:
- Measurement of vertex powers, cylinder axis, prismatic power and prism base setting at specified lens locations.
- Reference wavelength and conditions for optical measurements (linked to ISO 7944).
- Indication error and evaluation against reference lens true values (use of parameters defined in ISO 9342-1).
- Requirements for centration error (instrument residual prismatic effect with no lens).
- Test procedures (detailed test methods included):
- Checking indication errors, axis marker alignment, adjusting rail alignment and centration error.
- Special checks for automated focimeters (non-symmetric error, repeatability of vertex power).
- Procedures for measuring tinted lenses, astigmatic axis repeatability and eyepiece focimeters.
- Marking and manufacturer information: what must be supplied with the instrument to ensure proper use and conformity demonstration.
- Annexes: informative guidance on correction values, uncertainty evaluation for automated focimeters, reference lenses and user performance information.
Applications and who uses it
- Optical laboratories and calibration labs - to validate and calibrate focimeters.
- Spectacle lens manufacturers - to demonstrate product conformity with international lens standards.
- Dispensing opticians and ophthalmic practices - for reliable verification of lens prescriptions, orientation and marking (especially when measuring uncut or mounted lenses).
- Regulatory bodies and standards committees - for conformity assessment and procurement specifications.
Related standards
- ISO 7944 - Reference wavelengths for optical instruments
- ISO 9342-1 - Test lenses for calibration of focimeters (spectacle lens reference calculations)
- ISO 8429 - Graduated dial scale (relevant measurement interfaces)
Using EN ISO 8598-1:2014 ensures consistent, traceable focimeter performance and helps practitioners and manufacturers maintain measurement accuracy and regulatory compliance in ophthalmic optics.
