June 2013
Volume 54, Issue 15
ARVO Annual Meeting Abstract  |   June 2013
Assessment of the relationship between contact lens coefficient of friction and subject lens comfort
Author Affiliations & Notes
  • Jami Kern
    Global Medical Affairs, R&D, Alcon, Fort Worth, TX
  • Joseph Rappon
    Vision Care R&D, Alcon, Fort Worth, TX
  • Erich Bauman
    Vision Care R&D, Alcon, Fort Worth, TX
  • Ben Vaughn
    Biostatistics, Rho, Chapel Hill, NC
  • Footnotes
    Commercial Relationships Jami Kern, Alcon (E); Joseph Rappon, Alcon (E); Erich Bauman, Alcon Laboratories Inc. (E); Ben Vaughn, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 494. doi:
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      Jami Kern, Joseph Rappon, Erich Bauman, Ben Vaughn; Assessment of the relationship between contact lens coefficient of friction and subject lens comfort. Invest. Ophthalmol. Vis. Sci. 2013;54(15):494.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: To examine the relationship between subjective comfort and contact lens coefficient of friction among multiple soft contact lens materials.

Methods: A meta-analysis of clinical data (n=157) exploring the association between comfort and contact lens lubricity was conducted on 5 soft contact lens materials (delefilcon A, lotrafilcon B, balafilcon A , balafilcon A2, etafilcon A+). Subjective data for insertion comfort, overall comfort and end of day comfort were obtained from a database of clinical trials that included studies conducted between 2004 and 2011. Trials were included in the analysis unless they met exclusion criteria, including; extended or continuous lens wear, exclusively acute measures, multi-purpose lens care utilized, contra-lateral eye study design, small sample size (n< 30). The last on-eye treatment value for a lens was used and the association between reported comfort and the coefficient of friction, measured using the inclined plane method (Tucker et al), was assessed. Each comfort assessment (Insertion, Overall, End of Day) was analyzed separately in a mixed effect model with a fixed effect for the coefficient of friction and random effects for clinical trial and subject (for crossover studies). A serial gate-keeping approach was used to adjust for multiple comparisons.

Results: There were 117 females included in the analysis (74.5%) and the average age of subjects was 32 years. An inverse relationship was found between coefficient of friction and comfort. Coefficient of friction was highly predictive of each measure of comfort (all p<0.001), with higher coefficient of friction associated with lower comfort. Each of the outcomes showed a highly significant association between the respective comfort measure and coefficient of friction; the estimates were very similar for all 3 comfort outcomes assessed, with approximately a 0.025 reduction in coefficient of friction associated with a 1-unit improvement in comfort on a 10-point scale.

Conclusions: Using a database of clinical studies, we were able to demonstrate a strong relationship between lens coefficient of friction and subjective comfort. This association was not only statistically significant, but given the range of soft contact lens coefficients of friction, also clinically relevant. The lubricity of a lens should be taken into consideration when optimizing lens wear, especially as it relates to lens comfort.

Keywords: 477 contact lens  

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