People should try and avoid wearing their contact lenses to bed, one doctor has advised.
Ophthalmologist Dr Marc Werner told Fox News that "the worst problem" which occurs if you wear contacts for too long is the cornea breaking down.
He warned readers: "You can get a bad cornea infection called an ulcer, which can cause scarring of the cornea and even permanent loss of vision."
If you sleep in contact lenses, the risk of developing this type of infection increases ten-fold, Dr Werner said.
"I never recommend sleeping in contacts," he added.
David Wright, chief executive of the International Glaucoma Association, recently said the UK is likely to see a rise in the number of glaucoma sufferers in the years leading up to 2021.
He said the population in the UK is an ageing one, which means more people are likely to be diagnosed with the condition over the coming years and this growth in numbers could continue until as late as 2031.
by Alexa Kaczka