Company president Yoshinobu Nakashima said: 'They loved it. You know, there's not much for entertainment in those gymnasiums other than reading or watching TV.

'The glasses made it possible for them to read. It improved the quality of their lives immensely.'

The glasses scooped the Gold Award at the Asian Innovations Awards hosted by Credit-Suisse and The Wall Street Journal at the city's Four Seasons Hotel on Thursday, with organisers calling them an innovation 'that breaks with conventional processes in creative ways'.

Squinting in one eye and twisting the knobs on either side, Nakashima gave a demonstration by adjusting the lenses to suit his eyesight.

Two overlapping lenses move backwards and forwards incrementally, correcting vision for both near and far sight.

The Emergensee glasses were developed by Dutch professor Rob van der Heijde, of the VU University in Amsterdam, using lens technology by the late US Nobel laureate Luis Alvarez. They are manufactured in Malaysia using precision technology.

Dean Butler, a board member for Adlens, based in Oxford, England, said: 'It's for situations where the infrastructure is completely damaged and there's no-one able to make new glasses for you.

'Emergency workers can bring these in, and they can be held at government offices or post offices where people who need them can pick them up.'

The glasses sell in Japan for around HK$500 and are being included in medical and disaster-preparedness kits.

They are also proving popular with ophthalmologists whose patients experience fluctuating vision after eye surgery. Some experts have queried whether the Emergensee spectacles could damage the eyes if adjusted wrongly.

Van der Heijde said wearing a stronger prescription would not damage the eyes, and users could simply adjust the dials if they felt the prescription was inaccurate. However, he warned that the glasses may not be suitable for children whose vision was still developing.

The glasses are approved for sale in Japan and Europe and are awaiting approval in America.

But some optometrists are sceptical. 'I would not recommend these,' said John Li Yuk, the assistant branch manager for Optical 88 in Hong Kong's Times Square.

'Wearing them with the wrong prescriptions would cause headaches, and can make you need a stronger prescription.'

Adlens are concerned traditional optometrists may oppose the glasses, fearing they may put regular spectacle manufacturers out of business.

But Butler said: 'People thought the coffee market was saturated when Starbucks came in, but they've succeeded in expanding the market. We think these will do the same.'

Adlens pointed out that they are no cure for other eyesight problems that traditional glasses are needed to rectify, such as astigmatism.