Overview
ISO 16900-11:2013 specifies a laboratory test method for determining the field of vision of a respiratory protective device (RPD). It defines the equipment, headforms, mounting and mapping procedures, and the calculation of a quantitative Visual Field Score (VFS) that represents how much of the wearer's peripheral and central vision remains when wearing an RPD. This method supplements RPD performance standards (notably ISO 17420 series) and is used to assess visual obstruction caused by masks, facepieces and related respiratory interfaces.
Key topics and technical requirements
- Purpose and scope: Laboratory determination of the RPD field of vision for whole devices or parts intended to comply with performance standards.
- Apparatus:
- Apertometer (extended hemispherical dome) to capture the projected light/shadow (peripheral isopter).
- Headforms (Annex B) sized and dimensioned to represent anthropometric categories; light sources replace eyes.
- VFS plotting chart to map and count scoring points.
- Test principle: Light sources in a headform project onto the apertometer; the RPD casts a shadow defining the peripheral isopter. The isopter is plotted and compared with a predefined grid to derive the VFS.
- VFS calculation:
- The plotting chart assigns 118 grid dots (50 dots for the central 10° fixation area and 68 for the peripheral area).
- Count of grid dots inside the peripheral isopter = VFS; record the number of critical dots (four specially weighted peripheral points).
- Three separate fittings are required and an average total VFS reported.
- Device preparation & mounting: Don the RPD per manufacturer instructions, position symmetrically on the headform, and adjust straps as expected for normal wear.
- Environmental and tolerance limits: Nominal test conditions (ambient temperature and humidity) and tolerances are specified.
- Measurement uncertainty: Annex A defines how uncertainty, U, is applied to determine pass/fail relative to specification limits - overlapping uncertainty leads to a conservative (fail-for-safety) decision.
- Test report requirements: Number of specimens, preconditioning, accessories/filter simulators, headform used, meridian VFS results, critical points, and averaged VFS.
Applications and users
- RPD manufacturers and designers - to quantify and improve the visual ergonomics of masks, facepieces and full-face respirators.
- Test laboratories and certification bodies - to perform compliance testing to ISO 17420-related performance requirements.
- PPE procurement specialists and safety managers - to compare devices for tasks where peripheral vision is critical (industrial, emergency response, medical).
- Regulatory and standards bodies - to reference a harmonized laboratory method for vision assessment.
Related standards
- ISO 16900 series (Parts 1–4 and other parts under development) - other RPD test methods (inward leakage, breathing resistance, filter penetration, etc.).
- ISO 16972 - terms and definitions for respiratory protective devices.
- ISO 17420-3 - RPD performance requirements (thread connection) referenced for applicability.
Open preview (PDF)Respiratory protective devices — Methods of test and test equipment — Part 11: Determination of field of vision
