Go back fifty years or so, and whilst it wasn't unusual to see schoolchildren wearing glasses, those who wore them in the classroom were undoubtedly in the minority. So much so that at that time, just 7.2% of children were estimated to have short-sightedness, otherwise known as myopia.
Fast forward to more recent times and the rate of UK childhood myopia has more than doubled with some 20% of UK teenagers now estimated to need corrective lenses for short-sightedness.
Moreover, children are being diagnosed with myopia at an earlier age than before.[1]
The picture is equally alarming elsewhere, with the World Health Organisation (WHO) commenting that between 80% and 90% of school leavers in Southeast Asia are short-sighted.
The WHO also estimates that 40% of the world’s population will be short-sighted by 2030, rising to 50% by 2050.[2]
So, what has changed over the last fifty years to bring about such a rise in short-sightedness? One significant clue has come from research carried out following covid lockdowns. Various studies have demonstrated that enforced confinement in homes and the additional screen time required for homeschooling have led to a rapid increase in short-sightedness in school children. For example, one Chinese study revealed that the prevalence of myopia among elementary and middle school students in Shenzhen rose from 46.9% in 2019 to 50.2% in 2020.[3]
Now there is nothing new about the correlation between outdoor time and myopia. But these post-covid studies have demonstrated only too well the impact of a reduced amount of outdoor time, mainly when set alongside increased screen time.
That led the WHO to launch a "Be He@lthy, Be Mobile" initiative in March 2022.[4] Commenting that "myopia represents an important public health issue in the 21st century," the programme aims to educate parents, health professionals, educators and others on the importance of understanding, identifying, and treating short-sightedness.
Most importantly, the programme aims to encourage actions which can either delay the onset of short-sightedness or slow down the development of the condition and increased outdoor time is high on the action list. Further support for the link between outdoor time and a reduction in short-sightedness has come from a two-year study which concluded in November 2022 with the following:
“Increasing outdoor time reduced the risk of myopia onset and myopic shift in refractive error, especially in non-myopic children.” [5]
However, it also commented that the protective effect was related to the duration of exposure and light intensity, suggesting that it has to be the correct type of exposure at the right time. In other words, sending children out to play after dark may not have the beneficial effects that you might hope for!
Check out myopiafocus.org to find out more about myopia and the various management practices out there.