It was not until recently that people realised and took action against the significant growth of myopia incidence around the world.
Prevalence of myopia amongst preschool children in Hong Kong has tripled in 10 years
According to the statistics from the Centre for Health Protection of the Department of Health, the prevalence rate of myopia amongst preschool children in the city has tripled from 2.3% to 6.3% in ten years between 1996 and 2006.
Comparing 18.3 per cent of those at the age of six, the percentage of population with near-sightedness has climbed to 61.5 per cent for those aged 12.
A two-year collaborative screening effort by The Hong Kong Polytechnic University (PolyU)’s School of Optometry and the Hong Kong Paediatrics Foundation performed eye screenings on 5,148 schoolchildren from 2011. Based on the data gathered by the project, nearly 70 per cent of children above the age of 12 were myopic. Additionally, the average degree of myopia has increased to -2.11 Dioptres, compared to -1.45 Dioptres twenty years ago.
Neighbouring countries in East Asia are not faring any better. The findings are extremely alarming in South Korea, with over 96 per cent of 20-year-olds were found to be myopic. Even Western countries are catching up with this increasing trend.
“It's about 40 per cent in the U.S., compared to about 25 per cent in the 1970s,” said Dr. Michael Chiang, clinical spokesperson for the American Academy of Ophthalmology.
Exposure to sunlight might be a crucial factor in myopia prevention
Myopia is a multifactorial phenomenon and it develops from a combination of nature and nurture. A child with one or both parents that are short-sighted has two to eight times of risk of developing myopia compared to children with parents that have normal vision.
Long term myopia, especially severe myopia, defined as a refractive error of less than -5.00 dioptre in either eye by the World Health Organisation, leads to higher risk of developing glaucoma and cataracts.
Studies showed that increasing the time spent in outdoors environment is effective in protecting against developing myopia and its progression. An additional hour spent outside translates to an approximately 13 per cent decrease in risk.
Some researchers postulate a lack of exposure to sunlight during a child's formative years as the reason as their eyeballs are still developing. While the mechanisms behind remains unclear, theories suggest sunlight triggers dopamine release in the retina and the protective effects of blue light.
Trying to prevent children from developing myopia by making use of sunlight, Ian Morgan, a retired vision researcher at Australian National University, began his research in China by recruiting children to study in translucent classrooms under the sunlight.
On the other hand, the activities children are performing indoor are as equally important. For instance, the rising prevalence of electronic devices has definitely contributed to the worsening eye health.
Worsening vision an important public health issue
“Parents take it lightly, thinking it is simply a minor inconvenience that requires wearing glasses. But with near-sightedness progressing over the years, the eyes will grow so long that the retinas could be damaged,” warned Dr Patrick Wai-Ki Ting, External Secretary of the Hong Kong Society of Professional Optometrists.
Experts urged the government to invest more in programmes promoting eye health. Regular screening and active enquiry is important in children since they may not be able to recognise the potential severity of myopia. MIMS
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