Shortsightedness, also known as myopia, is a major public health issue worldwide. Although shortsightedness can be managed through interventions such as glasses and contact lenses, severe shortsightedness is associated with dangerous long-term conditions such as retinal detachment and macular degeneration. Limiting exposure to risk factors associated with shortsightedness is integral for preventing these conditions from occurring.

Genetics are a known factor in the development of the condition. As the prevalence of shortsightedness has been increasing globally, especially in children, environmental factors are also thought to be driving the trend. Two significant factors associated with increased risk of shortsightedness in children are the number of years spent in education and less time spent outdoors.

These factors have the potential to be linked, as class activities usually happen indoors. A November 2023 study published in Investigative Ophthalmology & Visual Science by Clark and colleagues aimed to investigate educational factors causing shortsightedness, more specifically about the effects of learning indoors. The researchers found evidence that a key driver of the negative effect that schooling has on eyesight, possibly almost half of its effect, is the fact that schooling takes place indoors.

Being indoors during schooling led to risk of early onset spectacle wear.

A Mendelian randomisation study utilised the genetic information (identified through genome-wide association studies) of the participants to provide information on the relationships between measures of shortsightedness (vision prescription measured via spherical equivalent refractive error and early age-of-onset spectacle wear) and number of years in education or time spent outdoors. Participants were derived from three cohorts, of which two were based in the UK and one was based in the Netherlands. The genome-wide association study for time spent outdoors was conducted using 280,891 adult participants from the UK Biobank for 9,572,557 genetic variants.

The analysis found that not being outside during schooling was a key contributing factor that led to a greater risk of shortsightedness and early age-of-onset spectacle wear. Not being outside was responsible for 40% of the relationship between years in education and shortsightedness, and 39% of the relationship between years in education and early age-of-onset spectacle wear. This study emphasises the role being indoors for schooling plays in the development of shortsightedness in children. Initiatives that encourage children to go outside during school hours could be instrumental in the prevention of cases of shortsight.

One such example is Taiwan’s Tian-Tian 120 programme, which encouraged school children to spend two hours per day doing outdoor activities. This has been effective in helping reverse the trend of increasing short-sightedness in this group, according to a November 2020 study published in the American Academy of Ophthalmology by Wu and colleagues. Programmes such as these hold great promise as they can be applied on a global scale.

GlobalData epidemiologists forecast that the number of prevalent cases of shortsightedness will increase from 1.29 billion cases in 2024 to 1.31 billion in 2029 in the 16 major markets (16MM: Australia, Brazil, Canada, China, France, Germany, India, Italy, Japan, Mexico, Russia, South Africa, South Korea, Spain, the UK and the US). GlobalData epidemiologists estimate that the number of prevalent cases of severe short-sightedness in the 16MM will increase from 120 million in 2024 to 122 million in 2029. Therefore, programmes such as Tian-Tian 120 hold great promise if applied on a global scale to both encourage the well-being of children and protect their eyesight in the long term.