Contact lenses
Contact lenses on the eye offer bacteria an ideal environment to grow. Factors promoting their success include: a nice surface for attachment, lots of nutrients and water for growth and reproduction (in your tears) and a favourable temperature (~37°C) and pH (~neutral). These conditions support the development of biofilms which are difficult to remove. Sometimes the bacteria are unable to hide from the immune system and the body’s defence responses are triggered. However, depending on the type of offending bacterium, the results can range from mild to potentially sight threatening.
Pseudomonas aeruginosa is the leading cause of sight-threatening bacterial infection of the eye (Green et al., 2008). Importantly, the care systems of most marketed contact lenses have appropriate efficacy against Pseudomonas aeruginosa, and also other common bacteria seen as culprits of microbial keratitis. However, as with most organisms, bacteria are constantly evolving to promote their own success. Therefore, research and development of biomaterials, particularly those in direct contact with the internal human body or its tissues, like contact lenses, should consider newly evolving mechanisms for survival in bacteria in order to prevent the formation of biofilms.
Further reading about biofilms and contact lenses
Green, M., Apel, A. and Stapleton, F. (2008) ‘Risk factors and causative organisms in microbial keratitis’, Cornea, vol. 27(1) pp. 22-7, https://doi.org/10.1097/ICO.0b013e318156caf2.