A new generation of contact lenses can significantly reduce the risk of severe eye infections, researchers said on Tuesday.

Wearers who keep their lenses in overnight can develop keratitis - inflammation or irritation of the cornea - but scientists found the new lenses cut that risk by fivefold.

“Those who choose to sleep in lenses should be advised to wear silicone hydrogel lenses, which carry a five times decreased risk of severe keratitis for extended wear compared with hydrogel lenses,” reported Dr. Philip Morgan of the University of Manchester in the British Journal of Ophthalmology.

He and his colleagues studied 118 patients with different degrees of keratitis in a year-long study. Each person provided details about the type of lens they used and whether or not they slept with them.

Specialists determined the degrees of severity of infection. Four types of lenses - rigid, hydrogel daily disposable, hydrogel and silicone hydrogel - were used in the study.

The scientists found no difference in the risk of keratitis among the four types of lenses in the people who wore them during the day.

But patients who wore silicone hydrogel lens and slept with them had a much lower risk of infection.

There are many types and causes of keratitis. It usually results from bacteria or fungi after the cornea has been scraped. It is typically treated with antivirals or antibiotics. Untreated cases can cause permanent eye damage.