Overview
ISO 18259:2014 - Ophthalmic optics - Contact lens care products - Method to assess contact lens care products with contact lenses in a lens case, challenged with bacterial and fungal organisms - specifies an antimicrobial efficacy end-point test to evaluate compatibility of contact lens solutions, lens cases and hydrogel lenses for disinfection. The method simulates real-world contamination introduced during patient handling by inoculating lenses in lens case wells with microbial challenge organisms (including the five ISO 14729 challenge organisms), adding product solution, and measuring microbial survival after labelled soak periods.
Key features:
- Tests the microbiological effect of preservative(s) in the presence of lenses and lens cases (soak step).
- Excludes oxidative disinfection systems for practical purposes.
- Produces log-reduction data to assess disinfection performance and compatibility.
Key topics and technical requirements
- Test principle: Inoculate lenses placed in lens case wells with bacterial and fungal organisms in organic soil, allow 3–10 minutes contact, then add the test solution and store for defined time points.
- Soak and sampling times: Minimum regimen soak (labelled), 24 h, 7 days, and maximum labelled storage; additional time points allowed.
- Lens & case selection: New, unused lenses (representative groups e.g., Group I, IV, V) and the manufacturer-recommended lens case(s) are evaluated.
- Challenge organisms & soil: Use the five challenge organisms specified in ISO 14729; organic soil prepared per Annex A (heat‑killed yeast + serum).
- Sample handling: Vortex each lens case before sampling, remove lens, withdraw aliquot, neutralize antimicrobial agents (validated neutralizing media or membrane filtration), perform serial dilutions and plate counts.
- Data endpoint: Calculate viable counts and log reductions for replicate wells; results inform risk assessment of compatibility.
- Environmental controls: Maintain and document storage temperature (20–25 °C), incubation conditions for recovery media, and validated neutralization procedures.
Practical applications and users
ISO 18259:2014 is used by:
- Contact lens solution and lens-case manufacturers for product development and compatibility testing.
- Microbiology and quality control laboratories performing regulatory and conformity testing.
- R&D teams assessing preservative efficacy in the presence of specific lens materials (hydrogel, silicone hydrogel).
- Regulatory affairs and submission dossiers where compatibility and disinfection claims require robust microbial data.
Benefits:
- Simulates in-use contamination to reveal preservative-lens/case interactions.
- Supports labeling claims for disinfection regimens and storage guidance.
- Provides data to combine with preservative uptake/release studies (ISO 11986) for comprehensive compatibility evaluation.
Related standards
- ISO 14729 - Microbiological requirements and test methods for contact lens care products (Stand‑alone test details, challenge organisms).
- ISO 18369 series - Contact lens vocabulary and measurement methods.
- ISO 11986 - Preservative uptake and release testing (recommended for complementary assessment).
Keywords: ISO 18259:2014, contact lens care products, antimicrobial efficacy, lens case compatibility testing, contact lens disinfection, hydrogel lenses, microbial challenge, ISO testing methods.