CL research given wide coverage

Contact lens research reported in last week's optician, highlighting the risks of sleeping in lenses, was widely publicised this week. However, the results of an as-yet-unpublished study due to appear in May are to challenge its findings (News, March 18).

Research, to be published in this month's British Journal of Ophthalmology (March 22) found that sleeping in contact lenses carried a significant risk of microbial keratitis (MK). However, the new-generation silicone hydrogel lenses cut that risk fivefold.
The findings are based on a year-long study of patients attending the Royal Eye Hospital in Manchester with acute eye problems.

All those wearing contact lenses were asked to supply details of lens hygiene, type, and pattern of wear, including whether they slept in them.

Specialists scored eye problems on the cornea according to their severity, 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, nine did so.

Four types of lenses were studied - rigid, hydrogel daily disposable, hydrogel, and silicone hydrogel. There were 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 there were some differences between lens types.

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.

However, Professor Nathan Efron told optician that a study of the incidence of contact lens-related microbial keratitis in Australia, to be presented at the ARVO meeting in Florida in May, had produced conflicting results.