By: Sherwin Loh

Behind the gigantic cinema screens at Shaw Lido, a restaurant-type dishwasher hums diligently.

But instead of cleaning plates and cups, its starring role is to wash the several hundred pairs of 3-D glasses worn by movie-goers after a screening.

After the glasses are run through the machine for two minutes, a staff member wipes them dry, packs them neatly into a box and returns them to the cinema hall for the next movie screening.

Worn to enjoy 3-D movies, the glasses allow one the thrill of perceiving objects popping out from the screen. Each pair, which can cost about $100, is reclaimed from the movie-goers after the show.

They can be used for about five years.

Since 3-D was introduced here in December last year, with the release of the animated cartoon movie Bolt, 10 cinema halls have been equipped to screen these films.

Tickets for such shows, which include the recent animated movie Up and the upcoming sci-fi film Avatar, cost $2 to $3.50 more than regular movie tickets.

But a health concern may arise when the 3-D glasses come in contact with body fluids like tears, or get tainted by food like popcorn or sweet liquids.

This may make the glasses an agent for the transfer of diseases and bacteria to others.

'In theory, if a person has an eye infection and leaves behind tears, it's possible for the bacteria or virus to be transferred to the next person if the glasses have not been cleaned thoroughly,' said Dr C.M. Pan, a general practitioner.

Four of the five local cinema operators said they clean the glasses after each use.

Filmgarde is the only operator which cleans the glasses daily, and 'as and when the glasses are found to be dirty in between sessions', said a spokesman.

For one operator, Shaw Organisation, speed and efficiency prompted it to rent a washing gadget and hire extra staff to take care of the eyewear.

'We are concerned about hygiene, so we took into account the recommendations of the manufacturer, who even told us the right temperature to wash the glasses,' said Mr Terence Heng, vice-president of media at Shaw.

The staff at Golden Village, Eng Wah and Cathay manually wipe each pair of glasses after they are used.

'We've a team dedicated to overseeing 3-D screenings and cleaning of 3-D glasses, which involves proper wiping and sanitisation with special cleaning cloth and skin-friendly sanitisers,' said a spokesman for Cathay.

Aside from Filmgarde, the other four operators said they have more glasses than seats in their 3-D halls, allowing for clean glasses to be handed out even for consecutive screenings. Golden Village, for example, has close to 2,000 glasses for use in its four halls that sit only 1,402. None of the operators has seen patrons return an extremely dirty pair of glasses.

The local method is more hygienic than that in the United States where cheap, disposable 3-D glasses are used in some cinemas. Glasses are dropped into a bin after the movie and ushers can pull out the same pair from it for the next patron.

This article was first published in The Sunday Times.