Overview
ISO 10943:2023 - Ophthalmic instruments - Indirect ophthalmoscopes is the fourth edition (2023) international standard that specifies minimum requirements and type test methods for hand-held, spectacle-type, and head-worn indirect ophthalmoscopes used to observe indirect images of the eye fundus. It supplements and, where differences exist, takes precedence over ISO 15004-1 and ISO 15004-2. The standard excludes condensing lenses, accessories, table-mounted Gullstrand-type instruments, and devices primarily intended for image capture/processing (e.g., scanning-laser systems).
Key topics and technical requirements
- Optical and dimensional criteria
- Interpupillary distance range: 55 mm to 72 mm
- Field of view (hand-held condensing at 500 mm): diameter ≥ 100 mm
- Largest illuminated spot (hand-held): ≥ 45 mm
- Headband circumference (adjustable): 520 mm to 640 mm
- Integral condensing systems: focal point 15–20 mm from instrument end; beam diameter at 500 mm 125–225 mm; field diameter at 500 mm 150–250 mm
- Optical accuracy limits include difference in magnification ≤ 5% and specified eyepiece power ±0.12 D
- Construction and function
- Light output adjustable from maximum down to 10% of maximum
- No visible reflections or scattered light; defocused beam must be homogeneous and achromatic
- Illumination alignment with viewing system within 1° vertically
- Binocular systems: no visible difference in brightness or colour between left and right channels
- Safety and light hazard
- Light safety classification and test methods are applied in accordance with ISO 15004-2; instruments without integral condensing systems are tested with the manufacturer‑specified condensing lens representing the worst‑case light exposure
- Testing and compliance
- All tests are type tests; measurement devices should have accuracy better than 10% of the smallest value tested; uncertainty handling follows ISO/IEC Guide 98-3
- Documentation and marking
- Required instructions for use, manufacturer details, safe condensing lens specifications, and conformity reference to ISO 10943:2023
- Permanent marking: manufacturer, model, and required IEC 60601-1 markings
Applications and users
- Device manufacturers designing or validating indirect ophthalmoscopes
- Test laboratories performing type testing and conformity assessment
- Regulatory bodies and notified bodies reviewing safety and performance
- Procurement specialists and clinical engineers specifying equipment for ophthalmic clinics
- Biomedical engineers and R&D teams focused on ophthalmic instrument design and compliance
Related standards
- ISO 15004-1 (general ophthalmic instrument requirements)
- ISO 15004-2 (light hazard protection for ophthalmic instruments)
- IEC 60601-1 (medical electrical equipment basic safety and essential performance)
- ISO/IEC Guide 98-3 (measurement uncertainty, GUM)
Keywords: ISO 10943:2023, indirect ophthalmoscopes, ophthalmic instruments, test methods, light hazard, condensing lens, binocular ophthalmoscope, IEC 60601-1, ISO 15004-2.
