Field of Science

What could be on your contact lenses?

I’ve just been watching ‘Monster Jellyfish Attack!’ (Yes I watch some strange programs in between X-factor and Eastenders!) and it reminded me of a weird microorganism I’m currently working with.
No – it’s not a tiny jellyfish; it’s actually a type of Amoeba species known as Acanthamoeba. Unlike bacteria and viruses, this is different (and a bit of a pain to work with as they’re easily contaminated and affected by the slightest change in temperature), and it actually feeds on gram-negative bacteria such as E. coli.
Eats bacteria? Sounds good doesn’t it? Wrong!

What is Acanthamoeba?
This microorganism is a particular problem with contact lenses (hence the title of this post). This amoeba is one of the main reasons contact lenses have to be left in a disinfectant solution before being used. Acanthamoeba polyphaga is a free-living pathogenic amoeba that lives in the soil and water. If contact lenses are not cleaned correctly, rinsed with water or contaminated due to poor hygiene then an infection is likely.
This Amoeba can cause’ Keratitis’ - which can be a potentially blinding infection of the cornea of the eye! So, disinfection of contact lenses is highly important. Hydrogen peroxide is one of the most effective disinfectants against this organism, and is used to clean most contact lenses.
Acanthamoeba polyphagia - Light microscope x1000

Acanthamoeba and me?
 So, I’m currently working with this organism – Why? If I’m not carefully I could blind myself!
Well, I’m working with it to hopefully increase hydrogen peroxide’s effectiveness against this organism (e.g. quicker kill time and lower concentrations to be used).
A quicker kill time would be great as it means less time leaving your contact lenses in disinfectant and more time wearing them. A lower concentration seems silly right? A higher concentration of hydrogen peroxide means more kill? Well hydrogen peroxide is quite a dangerous, flammable chemical so reducing this risk would be a good thing J

Worse things than going blind?
Not only can Acanthamoeba polyphaga cause blindness - it has also been shown, by the University of Bath, that MRSA can replicate inside of it! (causing more of a problem). Also, if you’re immunocompromised (HIV, chemotherapy), then this organism can cause ‘encephalitis’ - which is an infection of the brain.

So, now you know what could be lurking on your contact lenses – you’ll be making sure they’re thoroughly cleaned before wearing them!

References:   Huws, S. A., Smith, A. W., Enright, M. C., Wood, P. J. and Brown, M. R. W. (2006), Amoebae promote persistence of epidemic strains of MRSA. Environmental Microbiology, 8: 1130–1133. doi: 10.1111/j.1462-2920.2006.00991.x