Overview
ISO 18490:2015 - "Non‑destructive testing - Evaluation of vision acuity of NDT personnel" defines a standardized near‑vision acuity test for personnel performing NDT inspection. The standard specifies optotype design, test chart quality and sizing, controlled test conditions (illumination and distance), the test procedure, acceptance level, and qualification of personnel who administer the test. It addresses only near vision acuity in conditions similar to routine NDT inspection and does not cover colour vision or a full medical eye examination.
Key topics and technical requirements
- Test charts and optotypes
- Charts comprise two blocks (A and B), each with 10 lines of 5 E‑shaped optotypes, randomly rotated by multiples of 90°.
- Optotype heights (Annex A): Line 1 = 5.00 mm; 2 = 4.00 mm; 3 = 3.00 mm; 4 = 2.00 mm; 5 = 1.75 mm; 6 = 1.50 mm; 7 = 1.25 mm; 8 = 1.00 mm; 9 = 0.75 mm; 10 = 0.50 mm.
- Charts printed in black on white; print quality must be verified (approx. 10× magnification) and size checked (250 mm reference distance must be 245–255 mm).
- Test environment
- Illumination: visible white light, 500–750 lx measured at the chart.
- Eye‑to‑chart distance: 400 ± 25 mm; chart positioned perpendicular to line of sight.
- Candidates use the same eyewear they would wear in routine NDT (PPE or corrective lenses); temporary test lenses not permitted.
- Procedure
- Both eyes used together (binocular), candidate identifies orientation of each E (e.g., Up/Down/Left/Right).
- Administrator records responses line by line from left to right until the candidate reaches their limit.
- Acceptance level
- Acceptable near vision acuity = correct identification of all 5 optotypes on each of lines 1 through 9 inclusive.
- If failed, verify chart quality/conditions; repeat test with corrective eyewear if appropriate.
- Personnel administering test
- Must be trained and designated by a Level 3 NDT authority; designation documented.
Applications
- Use ISO 18490:2015 to verify near vision acuity for NDT inspectors, trainees, and certified personnel in industries such as aerospace, oil & gas, power generation, and manufacturing.
- Supports compliance with personnel qualification and certification schemes (ensures candidates meet the near‑vision element required for NDT competency).
- Useful for employers, NDT Level 2/3 supervisors, certification bodies, quality managers, and training organizations implementing vision checks as part of safety and competence programs.
Related standards
- ISO 9712 - Non‑destructive testing: Qualification and certification of NDT personnel (referenced for certification requirements).
- EN 4179 - Aerospace series: Qualification and approval of personnel for non‑destructive testing.
Note: ISO 18490:2015 is a standardized, non‑medical screening tool. Employers should consider referring personnel to medical eye specialists when broader visual acuity or health issues are suspected.
