Overview
ISO 11981:2017 - "Ophthalmic optics - Contact lenses and contact lens care products - Determination of physical compatibility of contact lens care products with contact lenses" - defines a standardized procedure and performance criteria for assessing the physical compatibility between contact lenses and lens care products, and for determining whether observed changes are reversible or irreversible. The standard guides laboratory testing that simulates real‑world use and compares measured lens parameters against baseline values and tolerances.
Key topics and technical requirements
- Scope and principle
- Measures changes in key lens characteristics after cycling in a care product and, when needed, after re‑equilibration in a standard saline solution.
- Baseline measurements are taken after equilibration in standard saline (pH 7.4 ± 0.1; nominal osmolarity 310 ± 5 mOsm).
- Selection and sample size
- Minimum of 10 test lenses per lens material × care product combination.
- Test lens groups should represent intended use (see ISO 18369-1 material groupings).
- Cycling protocols
- Simulate manufacturer instructions for use (volumes, temperatures, times).
- Typical temperature range: 20 °C to 25 °C.
- For daily-use care products: 30 cycles per lens.
- For scheduled products (e.g., enzymatic cleaners): cycles representing one month or ≥ five exposures.
- For rewetting/lubricating drops: protocols that simulate one month of on‑eye use.
- Measured properties
- Diameter (hydrogel lenses), curvature (rigid lenses), back vertex power (all materials), spectral transmittance (cosmetic/UV lenses), and physical appearance (surface defects, colour).
- Measurement methods referenced to ISO 18369‑3; tolerances referenced to ISO 18369‑2.
- Reversibility testing
- If changes exceed tolerances, lenses are re‑equilibrated in standard saline and re‑measured to classify changes as reversible or irreversible.
- Reporting
- Test report must include lens and product identification (lot/expiry), protocol, results (baseline and post‑test), laboratory name, responsible person and signature, and test dates.
Practical applications and users
- Intended for manufacturers of contact lenses and contact lens care products to validate compatibility claims.
- Useful for regulatory submissions, product development, quality control, and independent testing laboratories.
- Beneficial to clinical researchers and standards teams assessing material interactions, product labeling, and real‑world use simulation.
Related standards
Keywords: ISO 11981:2017, contact lens compatibility, contact lens care products, physical compatibility testing, standard saline solution, ophthalmic optics, contact lens materials.