Overview - ISO 11986:2017 (preservative uptake and release for contact lenses)
ISO 11986:2017 specifies general procedures to assess the uptake (absorption/adsorption) and release (leaching) of preservatives from contact lens care products into contact lenses. The standard defines sample preparation, selection of analytical methods, test conditions and sampling schedules for measuring preservative transfer between solution and new, unused contact lenses. It does not measure disinfection performance and applies only to lenses that have not been worn (deposits from wear make reproducible testing impractical).
Key topics and requirements
- Scope and limitations
- Applicable to new/unused lenses only; does not evaluate antimicrobial efficacy.
- Requires justification of chosen lens materials and care product(s).
- Test principle
- Lenses are immersed in the test solution at 25 °C ± 2 °C and preservative concentration is monitored until equilibrium.
- After equilibrium, lenses are transferred to saline (per ISO 18369‑3) at 37 °C ± 2 °C (typically 1 ml per lens) and release is sampled at set intervals (e.g., 1 h, 2 h, 4 h, 16 h) until no further release is observed.
- Analytical method selection
- The standard does not prescribe a specific assay; users must select validated analytical methods with suitable sensitivity, repeatability and reproducibility for the preservative studied.
- Sampling and data expression
- Uptake can be calculated by difference in preservative concentration in solution or by direct extraction from lenses.
- Volume of test solution must be large enough so lens uptake does not reduce preservative concentration by more than 25%; if >75% of preservative is absorbed, increase solution volume and repeat.
- Practical controls
- Account for container adsorption (use appropriate vessels or controls).
- Use sufficient replicate lenses and sampling points to ensure measured values exceed method detection limits.
Applications - who uses ISO 11986 and why
- Contact lens and lens-care product manufacturers: characterize preservative–material interactions during product development and quality control.
- Analytical and contract testing laboratories: design validated test protocols and report uptake/release profiles.
- Regulatory and safety assessors: evaluate potential for preservative-related ocular irritation or sensitization linked to lens materials or formulations.
- R&D teams: compare material families (hydrogel, silicone hydrogel, rigid gas-permeable) and screen changes to formulations or lens polymers.
Related standards
- ISO 18369‑3:2017 - referenced for saline composition and measurement methods.
- ISO 18369‑1:2017 - classification of contact lens material groups to guide representative lens selection.
Keywords: ISO 11986, preservative uptake and release, contact lenses, contact lens care, preservative leaching, ophthalmic optics, ISO 18369.
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