Acanthamoeba keratitis has once again created some unwelcome headlines for contact lens suppliers and practitioners.
In recent years, the cyst-forming microorganism has frequented the summer news pages, usually when holidaymakers make the mistake of swimming in their contact lenses and return home with more problems than they went away with.
A fresh South East-based study released by UCL and Moorfields Eye Hospital last month has now suggested a threefold increase in Acanthamoeba among contact lens wearers since 2011 (Optician 28.7.18).
The study also showed that reusable contact lens wearers were more likely to have used an ineffective contact lens solution, have contaminated their lenses with water or reported poor contact lens hygiene. The findings were published in the British Journal of Ophthalmology.
Lead author Professor John Dart, from UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust, said: ‘This infection is still quite rare, usually affecting 2.5 in 100,000 contact lens users per year in South East England, but it’s largely preventable. This increase in cases highlights the need for contact lens users to be aware of the risks.’
Professor Dart added that the most severely affected patients have less than 25% of vision or become blind following the disease and face prolonged treatment. A quarter of those affected require corneal transplants to treat the disease or restore vision.
The study was funded by Fight for Sight, Moorfields Eye Charity and Coopervision UK alongside support from the NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust.
Researchers collected incidence data from Moorfields Eye Hospital from 1985 to 2016. They found an increase dating from 2000-2003, when there were eight to 10 cases per year, to between 36-65 annual cases in the past few years.
Moorfields treats more than one in three cases of Acanthamoeba in the UK, meaning findings were expected to be relevant to the UK more broadly.
Researchers also conducted a case-control study of people who wear reusable contact lenses on a daily basis, comparing those who had a diagnosis of Acanthamoeba keratitis to those who had come in to Moorfields A&E for any other reason, from 2011 to 2014.
The case-control study included 63 people with Acanthamoeba keratitis and 213 without. They all completed a questionnaire, from which the researchers found that the risk of developing the disease was more than three times greater among people with poor contact lens hygiene, people who did not always wash and dry their hands before handling their lenses, those who used a lens disinfectant product containing Oxipol, and for people who wore their contacts while in swimming pools or hot tubs.
Showering and face washing while wearing contact lenses were also likely to be risk factors, researchers found.
Significantly, Acanthamoeba was also more commonly found in the UK than in other countries, due to higher levels found in domestic, as opposed to mains, water supplies, meaning water contamination of contact lenses continued to be of particular concern.
Dr Nicole Carnt, who completed the study at Moorfields before moving to the University of New South Wales, explained that hard water areas and water storage tanks in the UK were at the core of the problem.
She said while Australia had similar rates of domestic sink contamination as UK, the virulence of the Acanthamoeba seemed to be less in Sydney compared to the UK – with further tests being carried out.
Dr Carnt described Acanthamoeba as the ‘Trojan horse’ of the microbial world as it has the ability to host bacteria and fungi.
It has been found to be three times more prevalent in hard than soft water areas of the UK, where limescale builds up on the inside of pipes, ‘forming a surface for bacterial biofilm to grow on’. Described as a grazing organism, Acanthamoeba feeds on the bacteria as the pipe progresses to the domestic tap.
Meanwhile, water storage tanks in roofs of old houses have been found to harbour bacteria that are a food source of Acanthamoeba. ‘Traditionally this is the hot water supply to bathrooms, where most contact lens wearers insert and remove their lenses and conduct contact lens hygiene. In the latest study, we have found that swimming and using lenses in hot tubs is associated with a three times increased risk of infection,’ Dr Carnt said.
Although not reported in the paper, around 30% of the Acanthamoeba cases were in daily disposables. ‘It is important not to suggest that daily disposables will eliminate this disease although they may decrease the risk if water and poor hygiene factors are avoided,’ she added.
Researchers stressed the current outbreak was unlikely to be due to any one of the identified risk factors in isolation.
Professor Dart said: ‘People who wear reusable contact lenses need to make sure they thoroughly wash and dry their hands before handling contact lenses, and avoid wearing them while swimming, face washing or bathing. Daily disposable lenses, which eliminate the need for contact lens cases or solutions, may be safer and we are currently analysing our data to establish the risk factors for these.’
Dr Carnt added: ‘We now need to share this information as widely as possible with clinicians, contact lens practitioners and contact lens wearers, a strategy that has proved effective in the past in decreasing the incidence and burden of this severe eye infection.’
Public awareness of the infection has been bolstered in recent years by an awareness drive and ‘No Water’ sticker initiative driven by patient Irenie Ekkeshis, now part of the Acanthamoeba Keratitis Patient Support Group UK.
Ekkeshis said: ‘This research confirms what those of us affected by Acanthamoeba keratitis have suspected for some time: that incidences of this awful, life-changing infection are on the increase, and there’s more that should be done to prevent people from losing their sight to Acanthamoeba keratitis.
‘It is absolutely imperative that regulators and those working in the optical sector take the findings seriously, and use the recommendations to take immediate and urgent action on prevention. Contact lenses are medical devices and should be supplied with warnings regarding safe use.’
Scary number of non-compliant patients
This week ABDO launched a campaign encouraging consumers to take more care when using cosmetic lenses as part of their Halloween costume.
The optical body conducted a survey among 2,000 female patients, which revealed that 54% of respondents did not know that a contact lens could cause damage to the eye if not correctly fitted.
Meanwhile, 56% of respondents did not think it was important to seek professional help when purchasing lenses, and 61% bought their lenses from an online retailer, fancy dress shop or market-stall.
More than a third of the respondents said they would go and see a GP instead of an optician to resolve eye soreness and discomfort.
Its findings follow a survey by the College of Optometrists during National Eye Health Week last month, which unearthed poor habits and hygiene in using contact lenses and eye drops.
The college survey, which included 395 contact lens wearers and 1,311 patients who had used eye drops, and only 70% of respondents always washed their hands before inserting contact lenses.
Half of all users of eye drop users had never been shown how to use them correctly and more than half ‘miss their eye when inserting drops sometimes, or every time’.
Daniel Hardiman-McCartney, clinical adviser for the College of Optometrists, said: ‘We can also see that a lot of people struggle with inserting eye drops. Some people will use these for a short period of time, but others, such as those who have conditions such as
dry eye or glaucoma, may use them on an on-going basis and may not receiving the full therapeutic benefit.
‘One study found up to nine in 10 people affected by glaucoma struggled to instil their drops correctly. It’s easy to make sure that you are taking the appropriate steps to ensure good eye hygiene, be it putting in drops or contact lenses, you can consult our video series to ensure that you are getting it right.’