SIST EN ISO 11978:2017/A1:2020 PDF

Overview

EN ISO 11978:2017/A1:2020 - Ophthalmic optics: Contact lenses and contact lens care products - Labelling (Amendment 1) is a CEN-endorsed amendment to ISO 11978:2017. It updates labelling requirements to improve legibility and accessibility of manufacturer information on contact lenses and care-product packaging. The amendment (published October 2020) was adopted as a European Standard (EN ISO 11978:2017/A1:2020).

Key topics and technical requirements

• Minimum character/symbol size: All user-facing written information and symbols must be designed with a minimum height of 0.7 mm.
• Contrast requirements: For colour combinations other than black text on a white background, labels must achieve a contrast ratio of at least 3:1 between text/symbol colour and background.
• Colour space and conversions: Colour contrast calculations are to be performed using RGB / sRGB values. CMYK print values should be converted to RGB using a suitable conversion tool.
• Contrast computation method: Annex A (informative) defines the calculation workflow:
  • Normalize 8‑bit RGB values to sRGB, apply nonlinear linearization (threshold ~0.04045 and gamma ≈2.4).
  • Compute relative luminance using IEC coefficients (L = 0.2126·R + 0.7152·G + 0.0722·B in linear sRGB).
  • Calculate contrast as (L1 + 0.05) / (L2 + 0.05), where L1 is the lighter luminance. Black on white has a maximum contrast of 21:1.
• Guidance and examples: Annex A includes worked examples of acceptable and unacceptable colour combinations and references standards/guidelines such as IEC 61966-2-1 and WCAG 2.1.

Applications and who should use it

• Contact lens and care-product manufacturers - to ensure packaging and instructions meet legibility and accessibility requirements for market access in CEN countries.
• Regulatory and compliance teams - to verify label conformity during product approval and audits.
• Packaging designers and print vendors - to select colour schemes, fonts and print processes that meet the 0.7 mm size and 3:1 contrast constraint after CMYK-to-RGB conversion.
• Quality assurance and testing labs - to perform contrast measurements and provide evidence of compliance.
• Optical retailers and healthcare providers - to understand label standards for patient safety and product information clarity.

Related standards

• IEC 61966-2-1 (sRGB / colour management)
• WCAG 2.1 (Web Content Accessibility Guidelines) - referenced for contrast methodology and accessibility principles
• CIE 1931 (colour spaces / tristimulus values)

Keywords: EN ISO 11978, contact lens labelling, ophthalmic optics standard, label contrast ratio, sRGB contrast calculation, CMYK to RGB conversion, packaging compliance, accessibility.