ONE of the most advanced endoscopy units in the world has just opened at the Prince of Wales Hospital, enabling doctors to treat more than 3,000 extra patients each year. As the technique takes on an increasingly important role in modern medicine, the decade-old endoscopy facilities at the hospital have become outdated and overwhelmed. Last year, the facilities treated more than 10,000 patients. It is hoped the Shaw Endoscopy Centre, which officially opened last Friday, will be able to boost the quantity and quality of work by 30 per cent. The director of the centre, Dr Sydney Chung Sheung-chee,, said: ''The use of endoscopy has risen dramatically over the past decade and this centre will allow us to cope with the increased work load and provide a better service.'' The centre was built by the Hospital Authority but a donation of $7 million from Sir Run Run Shaw allowed the purchase of some of the most hi-tech equipment available, including a digital X-ray machine. Special features also include state-of-the-art video endoscopic equipment, a computerised image storage and reporting system and closed-circuit television monitoring of all endoscopy rooms. An endoscope is a tube which has a tiny video camera at its tip which transmits the image from inside the body on to a television screen. The ability to see inside the body directly has greatly enhanced a doctor's ability to make an accurate diagnosis. It is also possible to perform treatment by inserting accessories through the endoscope. Many diseases that needed open surgery in the past can now be treated by endoscopy, with the risks and suffering of an operation avoided. Dr Chung said: ''The convalescence and recovery are shortened and the cost of a hospital stay reduced, which are important considerations for the Prince of Wales Hospital where beds are always in short supply.'' Olympus Optical Company has provided the centre with 90 video endoscopes which will allow it to function as a training centre. Dr Chung said: ''Video endoscopes allow a number of doctors to watch what is going on on a video screen at one time, so we can train more doctors to use the technique.'' The centre will also provide a better environment for patients, with an eight-bed recovery area for day patients, five endoscopy rooms, a waiting area and a cleaning and disinfection section. A combined endoscopy unit was set up at the Prince of Wales Hospital in 1984 and over the past 10 years it has established itself as a world-leading centre of excellence in therapeutic endoscopy with many new treatment procedures pioneered in the unit. The team has concentrated on developing new treatments for diseases prevalent in Hong Kong, including obstructive bile duct stones and ulcer bleeding. Doctors at the hospital developed a method of controlling ulcer bleeding by injecting drugs through the endoscope. The technique has now gained international recognition and is the most commonly used method in stopping ulcer bleeding worldwide. An international workshop on therapeutic endoscopy is held at the hospital every year. It has gained international acceptance and is now an important event on the calendar of international endoscopy. In 1993, more than 300 endoscopists from 24 countries attended the workshop, while staff from the unit have been invited to lecture and give live demonstrations all over the world.