A new study has led scientists to urge contact lens wearers to look after their eyes following an outbreak of a rare infection which can cause blindness.
Researchers have noticed a three-fold rise in the number of cases of acanthamoeba keratitis since 2011 in south east England.
The infection that is preventable, causes the cornea, to become painful and inflamed and contact lens wearers are most at risk.
Left untreated, the amoeba can burrow into the cornea and cause blindness over a period of months.
Researchers from Moorfields Eye Hospital checked medical records since 1986 to analyse and compare rates of the infection.
They found between 2000 and 2003 there were eight to 10 cases of acanthamoeba keratitis recorded per year at the hospital. However, this rose to between 35 to 65 cases annually from 2011 to 2016, the study published in the British Journal of Ophthalmology found.
According to experts, the most severely affected patients are left with less than 25 per cent of their vision or become blind after having the infection.
Acanthamoeba, which feeds on bacteria, can be present in all forms of water - such as swimming pools, hot tubs, and even showers.
Reusable contact lens wearers with the eye infection are more likely to have used ineffective contact lens solution.
Or they may have contaminated their lenses with water or to have reported poor hygiene habits, the researchers said.
Showering, swimming and using hot tubs while wearing contact lenses are also risk factors.