More than 11 percent of six-year-old Hong Kong kids must wear glasses - the highest proportion in Asia.
That comes with the number of bespectacled children soaring as they enter primary school, leading an expert to slam the education system as "toxic to children."
Nancy Yuen Shi-yin, president of the College of Ophthalmologists, said the situation is worrying as short-sightedness - myopia - increases with age. That means more risks for diseases due to elongation of the eyeballs.
A team of experts from the Chinese University has been checking myopia in 13,599 children aged from four to nine since 2015.
It put myopia at 7.7 percent for four-year-olds but 44.5 percent for those aged nine.
Lead researcher Jason Yam Cheuk-sing said for six-year-olds it was 11.4 percent compared to 7.4 percent in Beijing, 6.6 percent in Singapore, 5.9 percent in India and 5.2 percent in Shanghai.
He pointed to the local education system as the cause.
"Children have to spend hours on revision and homework, when a massive amount of reading at a close distance will threaten the health of the eye," he said.
And myopia can be passed down from parents as eyeball length is affected by genes.
"We have collected information on parents and found 77.7 percent were also short-sighted, with 12.6 percent suffering from serious myopia," he said. "It's similar to height, which is often passed genetically. The chances of children developing myopia increases when parents suffer from serious short-sightedness."
Nicholas Fung Siu-kay, a clinical assistant professor at the University of Hong Kong, said: "People with serious short-sightedness have eyeballs that are 10 percent longer than those of healthy people.
"They are therefore prone to conditions such as retina detachment, cataracts and macular degeneration, all of which can lead to permanent blindness."
Fund said patients with early retina detachment - tiny holes at the edge of the retina - will show symptoms including flashes or black spots.
Conventional treatment includes laser work, he said, but it may require more complicated surgery.
For macular degeneration, patients may find eyesight deteriorating within a short time and see distorted images. It can be treated by injections to boost the growth of blood vessels on the retina and surgery for more serious conditions.