Overview
EN ISO 10939:2017 - Ophthalmic instruments: Slit‑lamp microscopes specifies requirements and test methods for slit‑lamp microscopes used to provide slit illumination and magnified observation of the eye and adnexa. Published by CEN/ISO, this standard is intended for the design, testing and conformity assessment of slit‑lamp microscopes (excluding accessories such as photographic equipment and lasers). Where differences exist, EN ISO 10939:2017 takes precedence over ISO 15004‑1 and ISO 15004‑2.
Key topics and technical requirements
- Scope and precedence: Applies together with ISO 15004‑1 (general ophthalmic instrument requirements) and ISO 15004‑2 (light hazard protection); EN ISO 10939:2017 overrides those where conflicts exist.
- Optical requirements (Table 1): includes numerical tolerances such as:
- Magnification tolerance: ±5%
- Left/right magnification difference: ≤3%
- Interpupillary adjustment range: 55 mm to 72 mm
- Slit image: minimum width 0.2 mm, minimum length 8.0 mm, with strict parallelism and shape criteria
- Focus and alignment tolerances: axial and lateral focus tolerances (e.g., axial Δa ≈ ±0.5 mm; lateral ≈ ±0.35 mm), and permissible shift in object plane ≤0.4 mm
- Dioptre scale calibration error: ±0.25 D at zero; typical adjustment ranges (e.g., −5.00 D to +5.00 D; −4.00 D to +2.00 D for high‑eye‑point eyepieces)
- Exit pupil difference between left and right systems: ≤1.5 mm
- High eye point eyepiece: if claimed, exit pupil clearance must be ≥17 mm to allow spectacles.
- Construction and performance: requirements for slit edge quality, even illumination, absence of stray light/contrast loss, and minimum resolving power at high magnification.
- Optical radiation / light hazard: classification into Group 1 or Group 2 per ISO 15004‑2 with specific test methods and exposure limits; additional measures required if used with supplementary lenses (e.g., 90 D Volk lens).
- Test and measurement rules: type testing; measurement devices must have errors smaller than 10% of the smallest value to be determined; results evaluated statistically.
Applications and users
- Medical device manufacturers designing and producing slit‑lamp microscopes for ophthalmology.
- Test laboratories and conformity assessment bodies performing type testing and verification to EN ISO 10939:2017.
- Regulatory and procurement specialists ensuring devices meet optical safety and performance criteria.
- Clinical engineers and optometrists/ophthalmologists involved in device selection, maintenance and safety checks.
Related standards
- ISO 15004‑1 - Fundamental requirements and test methods (general ophthalmic instruments)
- ISO 15004‑2 - Light hazard protection for ophthalmic instruments
- IEC 60601‑1:2005 + AMD1:2012 - referenced for medical electrical equipment safety where applicable
Keywords: EN ISO 10939:2017, slit‑lamp microscopes, ophthalmic instruments, optical requirements, light hazard protection, ISO 15004‑2, high eye point eyepiece, dioptre calibration.
