Overview
ISO 5868:2025 - Ophthalmic optics and instruments: Anomaloscopes for the diagnosis of red‑green colour vision deficiencies specifies performance, optical and technical requirements for anomaloscopes that test red‑green colour vision using the Rayleigh equation (matching a red‑plus‑green mixture to a yellow). The standard ensures that measured values on an examinee’s eye are physiologically meaningful and independent of the instrument’s technical characteristics, enabling reproducible clinical and occupational testing.
Key topics and technical requirements
- Scope and purpose: Applies to anomaloscopes designed to examine red‑green colour vision via the Rayleigh match.
- Spectral characteristics: Chromaticity and equivalent wavelength limits for red, green and yellow lights are defined (including spectral half‑power bandwidths) to ensure consistent colour stimuli.
- Stimulus geometry and luminance: Test field size specified as (2.0 ± 0.2)° visual angle (or equivalent area) and luminance/retinal illuminance limits (e.g., ~4.5 cd/m² ± tolerances) to standardize visual conditions.
- Graduation and mean standard match: Linear red‑green mixture scale with defined end points (0 = 100% green, R = 100% red) and a specified mean standard match for the 2° standard observer.
- Neutral adaptation: Requirement for a white adapting field (correlated colour temperature 2 500 K–6 500 K) and alternation rates to avoid chromatic adaptation.
- Conformity testing and uncertainty: Type‑tests for conformity, use of the CIE 2° standard observer, and measurement uncertainty assessed per ISO/IEC Guide 98‑3 (GUM) with 95% confidence.
- Marking and documentation: Permanent instrument marking and required accompanying documents (instructions, maintenance/calibration, reference to ISO 5868:2025).
- Calibration and test methods: Clause references test methods for spectral, luminance and chromaticity verification and an annex explaining equivalent wavelength derivation.
Applications and who uses this standard
- Manufacturers of anomaloscopes: To design and validate devices that meet international performance and safety criteria.
- Clinical and occupational screening services: Ensures reliable diagnosis of red‑green deficiencies for medical, aviation, maritime or other safety‑critical roles.
- Calibration and test laboratories: For type testing, calibration, and conformity assessment of anomaloscopes.
- Regulators and procurement teams: To specify compliant instruments in tender documents and certification processes.
Practical benefits include improved reproducibility of colour vision measurements, harmonized test results across devices, and clearer traceability for clinical and occupational decisions.
Related standards
- ISO 15004-1 - Ophthalmic instruments - Fundamental requirements
- ISO/CIE 11664‑1 - Colorimetry (CIE 2° standard observer)
- ISO/IEC Guide 98‑3 (GUM) - Uncertainty of measurement
- IEC 60601‑1 - Medical electrical equipment, basic safety and essential performance
Keywords: ISO 5868:2025, anomaloscope, colour vision, red‑green deficiency, Rayleigh equation, spectral characteristics, chromaticity, luminance, equivalent wavelength, ophthalmic optics.