Preventable Eye Infection Cases Rise for Contact Lens Users

Peter Russell

October 04, 2018

Researchers have warned of a new outbreak of a rare but preventable eye infection affecting people in the UK who wear contact lenses.

Acanthamoeba keratitis causes corneal inflammation and pain. 

Around a quarter of patients infected may lose most of their vision or become blind as a result of the cyst-forming microorganism. Those most severely affected require more than 10 months of treatment, 38 months follow-up, 31 hospital visits, and require corneal transplants, say researchers from University College London (UCL) and Moorfields Eye Hospital.

Vision Loss and Blindness

Acanthamoeba species are commonly found in air, soil, dust, and water. Infection is rare, as most people develop antibodies, but the surface of the eye is particularly susceptible to infection.

The researchers initiated an investigation to substantiate claims that incidence of the disease had increased in the UK in recent years.

The study, published recently in the British Journal of Ophthalmology , found a threefold increase in Acanthamoeba keratitis since 2011 in south-east England, where patients in this study were commonly based. However, this increase is likely to be replicated in other parts of the country, particularly for hard water areas, the researchers said.

Data from Moorfields between 1985 and 2016 was analysed. It revealed 36 to 65 cases annually in the past few years, compared with eight to 10 cases seen between 2000 and 2003.

Contact Lens Hygiene

The researchers identified several potential causes, including poor hygiene when handling contact lenses, not washing and drying hands effectively while handling contact lenses, and swimming or bathing while wearing contact lenses.

Medscape News UK asked Dr Neil Ebenezer, director of research policy and innovation at Fight for Sight, which helped to fund the study, about the disease, the research, and its implications.

Q&A

Medscape News UK: Can you describe this Acanthamoeba disease?

Dr Ebenezer: There are some species that exist that can, if in the eye, cause a problem. And when it does cause an issue, it generally affects the cornea, and there it forms an inflammation. It becomes often painful, inflamed; and it's a cyst-forming microorganism, so some of the cyst occasionally persists and then you can get the lapsing of the disease.

People will treat it with antibiotics or steroids, and that should actually reduce the inflammation and infection. But because a cyst can actually be embedded into the cornea, they can reoccur, so sometimes it's quite a prolonged treatment for some patients.

Medscape News UK: How common is this problem?

Dr Ebenezer: In terms of numbers, this is still relatively small. It's mainly from Moorfields, so it's really looking at the south-east [of England], where the majority of patients would come from.

For people who get this condition, it is hugely debilitating. And for 25% of people, this leads to cases where they will have significant erosion in their vision. And some people can actually become blind from this disease. And a smaller portion of patients might require corneal transplants or corneal grafts.

Medscape News UK: Why is water identified as a particular problem for contact lens wearers?

Dr Ebenezer: When we bathe and when we shower, it is very fleeting. It doesn't persist in the eye – it is washed away, and you blink, and it will be removed.

But obviously when you have contact lenses, that is then held and placed over the cornea. So, any microorganisms that get in there will then be persisting in the eye and more likely to cause infection.

The water companies will look at faecal contamination; they will have the chlorination that goes into water to clean things. But because of the nature of these microorganisms, they will persist into our drinking water. They pose no risk to health if we drink or ingest it.

Medscape News UK: Are all contact lenses equal?

Dr Ebenezer: It's important to make a distinction between re-usable contact lens users and disposable contact lenses.

This study focuses very much on re-usable contact lens wearers.

Medscape News UK: This is a preventable infection, so how can it be prevented?

Dr Ebenezer: Follow good hygiene, in terms of having an effective disinfection system; use good contact lens hygiene practice; and then reduce exposure to water while using lenses – removing lenses before showering or going into the swimming bath.

The other one is drying your hands well before you touch your lenses again.

Carnt N, Hoffman JJ, Verma S, et al Acanthamoeba keratitis: confirmation of the UK outbreak and a prospective case-control study identifying contributing risk factors British Journal of Ophthalmology Published Online First: 19 September 2018. doi: 10.1136/bjophthalmol-2018-312544. Abstract.

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