The Federation of Ophthalmic and Dispensing Opticians (FODO) has issued guidance to its members telling them to stop using test lenses on more than one person immediately.

The lenses are used in the fitting of hard lenses, gas-permeable lenses and some soft types.

The Department of Health issued a warning after speaking to scientists on its Spongiform Encephalopathy Advisory Committee (Seac).

The danger is posed because the eyes can carry material that will pass on the brain disease, and trial lenses are often used by many people.

Evidence so far

The committee's chairman Sir John Pattison described the government's action as a "precautionary measure" and said the risk of transmission was extremely small.

However, he confirmed that material capable of transmitting the disease was found in the eye.

"The eye is a very specialised organ in terms of its development - it's really an extension of the brain," Sir John told the BBC.

"You can find the agent of BSE at the back of the eye - the retina - and we know from classical CJD that you can transmit it from one patient to another by putting in a corneal graft.

"Contact lenses are likely to come into contact with the cornea, and it may be that they pick up cells that contain the transmissable agent."

He said there was no evidence that anyone had died of CJD as a result of wearing test contact lenses, and people should not be worried about their everyday contact lenses.

Much more study would be needed to determine if there was a real risk, but in the mean time it would be best practice for opticians to throw away test lenses after their first use, he said.

Government action confuses opticians

A Department of Health spokeswoman said: "Immediately acting on concerns about multiple-use trial contact lenses, Frank Dobson asked Seac to consider the issue at their meeting on 3 June."

The government has asked opticians to not to re-use lenses but will not develop a formal ban on the practice.

However, Bob Hughes, general secretary of FODO, said opticians had been confused by the government's approach.

He said: "We knew nothing about this until I saw a few lines from Frank Dobson in the middle of the night.

"We are concerned about the way the advice has been published.