New contact lenses cause less infections

Mar 21 2005

Sleeping with your contact lenses in can give you a nasty eye infection (keratitis), but now a new generation of silicone hydrogel lenses cuts that risk fivefold, according to research in the British Journal of Ophthalmology.

A year long study of patients attending the Royal Eye Hospital in Manchester, UK, with acute eye problems, collected data on all those wearing contact lenses -on lens hygiene, type, and pattern of wear, including whether they slept in them.

The severity of eye problems on the cornea was scored by specialists, a score above 8 denoting severe keratitis. Eighty were scored below 8, defined as 'non-severe keratitis,' and 38 were scored above.

Among the 80 who scored below 8, 18 slept in their lenses. Among the 38 with severe keratitis, 9 did so. Rigid, hydrogel daily disposable, hydrogel, and silicone hydrogel lenses were studied. There proved to be no differences in risk of severe keratitis between the different types of lenses when they were worn during the day but the risk of severe keratitis rose when lenses were slept in, and differences between lens types were seen.

Rates were 96 per 10,000 wearers a year for hydrogel lenses, compared with almost 20 per 10,000 wearers a year for silicone hydrogel lenses - a fivefold difference.Almost 3 million people wear contact lenses in the UK, around 55,000 of whom live in the catchment area served by the hospital, including 30,000 hydrogel lens wearers and 1700 silicone hydrogel lens wearers.

The researchers found that those wearing hydrogel lenses while they slept were five times more likely to develop severe keratitis than those wearing silicone hydrogel lenses.

They recommend that those who choose to sleep in lenses should wear silicone hydrogel lenses, which carry a five times decreased risk of severe keratitis for extended wear compared with hydrogel.

Click here to view the paper in full