There is a theoretical risk that v-CJD can be spread by contact with infected eye or central nervous system tissue.

The ban, announced on Thursday by the Department of Health, will apply to optical equipment that comes into direct contact with patients' eyes.

It follows a precautionary ban on the re-use of trial contact lenses announced in June.

The measure, which could cost the optical industry millons of pounds, follows advice from government experts on the Spongiform Encephalopathy Advisory Committee (SEAC), who are monitoring the spread of BSE.

SEAC has also advised surgeons "wherever possible" to use disposable instruments on operations involving the central nervous system, eye tissue or tissue from the lymph system.

The commitee is seeking a blood test that would enable v-CJD to be detected before death, enabling scientists to determine its incidence in the population at large.

At a news conference announcing the changes, Deputy Chief Medical Office Dr Pat Troop said there was only "a theoretical risk" of the fatal brain disease spreading between people, but said the government was commited to minimising that risk.

No public benefit

CJD causes the brain to develop a spongey appearance

The College of Optometrists said there had been no reported cases of CJD being transmitted via a contact lens fitting anywhere in the world, and argued the ban would not improve public safety.

Stopping the re-use of equipment that was used daily in clinics around the country for the diagnosis and treatment of many eye problems would cause "chaos" and result in greater waiting times.

Gwyneth Morgan, president of the college, said: "We are surprised that the Department of Health has taken the stance it has in the light of its continued call for the use of evidence based medicine.

"We believe that in these circumstances, actions of this nature do not make any sense at all.

"The public, and especially contact lens wearers, should be assured that their safety has always been, and will continue to be, paramount to every optometrist in this country."

Most of the equipment now banned is used in hospitals, but one machine, the tonometer, used to check for the debilitating eye condition glaucoma is commonly used by high street opticians.

One solution could be to develop disposal membranes fitted to machines and thrown away after use.

47 CJD deaths

SEAC said 47 people had now died of new variant CJD.

However, SEAC's acting chairman Professor Peter Smith warned that it was too early to estimate the eventual death toll.

Professor Smith, of the London School for Hygiene and Tropical Medicine, said: "Much depends on how many cases there are going to be as a consequence of exposure to BSE-contaminated meat.

"We just cannot know how many that is going to be.

"The estimates vary from less than 100 to hundreds of thousands, depending on assumptions you make about how long the incubation period is going to be."

Britain could be at the start of the epidemic, he said, but there had not been a rapid increase in cases.