Neeka Sharifi 

Summary

The potential effects of childhood screen use have attracted considerable public attention. Parents are often warned to reduce screen time due to concerns regarding the increasing prevalence of childhood myopia, with blue-light glasses being widely marketed.

Research has associated digital screen time with childhood myopia, but identifying a causal relationship continues to cause difficulty. Screen time is often associated with reduced outdoor activity and other near-work activities, which poses challenges to determine the contribution of each factor.

There is currently no convincing evidence that blue light from screens causes retinal damage, hence blue-light filtering glasses are unlikely to make much difference to temporary eye strain. In comparison, randomised trials suggest stronger evidence that spending time outdoors acts as a protective factor against the onset of myopia.

This commentary considers the important message that children who have more outdoor time are at a reduced risk of developing myopia. It highlights the importance of shifting the focus from solely screen time restrictions to promoting sensible near-work activities and increasing time spent outdoors.

Introduction

Concerns about the potential effects of screen use on children’s eye health have generated increasing public concern. Parents are often warned that smartphones, tablets and computers may be damaging their children’s eyes, with blue-light filtering glasses being widely marketed to reduce these risks. At the same time, the worldwide prevalence of myopia is increasing, with estimates that almost half of the global population could be myopic by 2050 (1).

Although these concerns are understandable, the evidence which links screen use to eye health is not as clear as public discussions may suggest. Research has identified associations between screen time and myopia but also highlighted factors such as other near-work activities and reduced outdoor time as factors to consider. This is important to account for when providing advice to families. Discussions can often focus on how many hours a child is spending using digital devices, rather than considering how much time they spend outdoors.

The epidemiology and management of progressive myopia have previously been reviewed in this journal (2). This commentary provides a complementary perspective by examining the evidence behind parental concerns regarding screen use and highlights the importance of increasing outdoor activity in preventing childhood myopia. The aim is to encourage ophthalmologists to provide balanced and actionable advice to families.

The Rise of Childhood Myopia

The increasing prevalence of myopia is a significant public health concern. 23% of the global population was estimated to be myopic in 2000, and this is projected to rise to 50% by 2050. High myopia is expected to affect almost one billion people. (1)

Although myopia prevalence is particularly high in East Asia, its prevalence has also increased in the UK. Research involving white children aged 12-13 years found that myopia prevalence has more than doubled since the 1960s, with an increase from 7.2% to 16.4% (3).

Myopia is often considered a refractive error that can be corrected with glasses or contact lenses. However, high myopia is associated with increased risks of myopic maculopathy, glaucoma and retinal detachment. Children who develop myopia earlier in childhood are at particular risk of progressing to high myopia (2). Hence, preventing or delaying the onset of myopia in childhood is essential to reduce risk of future sight-threatening disease. It is therefore vital to understand which factors contribute to its development based on evidence to help clinicians provide optimal advice to families.

What Does the Evidence Say About Screens and Myopia?

The association between screen time and myopia has been investigated in several studies. A systematic review of 33 studies found an association between smart device screen use and increased odds of myopia, with an odds ratio of 1.26. This rose to 1.77 when combined with computer use (4).

More recently, a systematic review and dose-response meta-analysis involving over 335,000 participants reported that each additional hour of daily screen time was associated with approximately 21% higher odds of myopia. The association appeared to increase mostly between one and four hours of daily screen use (5).

These findings suggest that screen time may be an important factor when looking at childhood myopia. However, there are several limitations to consider when analysing the results.

The included studies were observational, which can identify associations but are not able to establish a direct causal relationship. Most studies relied on questionnaire-based estimates of screen time, which may not accurately reflect children’s device use. Differences between these studies and the influence of other factors make these findings more challenging to interpret (4).

Separating screen use from other activities associated with myopia is one of the main challenges. Children who spend more time using digital devices, may also spend more time embarking on other forms of near work, including reading or studying. They may also be spending less time outdoors. It is difficult to assess whether the observed association is solely related to screens or can be attributed to these accompanying behaviours.

Overall, the current evidence supports an association between digital screen time and childhood myopia, but it does not establish that screens are more harmful compared to other forms of near work. Screen use therefore should be looked at alongside other lifestyle and environment factors rather than the sole explanation for the increasing prevalence of myopia.

Blue Light and Digital Eye Strain

Alongside concerns regarding myopia, parents may also be worried about blue light from screens damaging the retina and that screen use causes harmful eye strain. Blue- light filtering glasses are often marketed to protect eyes and reduce the discomfort associated with screen use.

However, there is currently no clinical evidence that blue-light emitted by screens causes retinal damage. A Cochrane review of 17 randomised controlled trials investigated the effects of blue-light filtering glasses in adults. The review found that these lenses make little or no difference to eye strain associated with computer use. The effects on retinal health were not evaluated in clinical trials (6). Although these findings were based on adults, there is no evidence suggesting that blue-light filtering glasses would provide any benefit in children either.

Digital eye strain, however, is a recognised problem associated with prolonged screen time. Symptoms can include headaches, dry eyes, blurred vision and visual discomfort. These symptoms are temporary and can be addressed through simple measures such as regular screen time breaks, correction of any underlying refractive errors and appropriate viewing distances (7).

It is hence important to differentiate between temporary symptoms associated with prolonged screen time and claims in relation to permanent retinal damage. Families should be encouraged to shift their attention from blue-light filtering glasses which have shown little benefit to other measures that may have remained unaddressed.

The Importance of Outdoor Time

In comparison to the evidence surrounding screen use, there is stronger evidence supporting time outdoors being protective against the onset of childhood myopia.

Observational studies demonstrated that children who spend more time outdoors are less likely to develop myopia, independent of differences in near work activities (8). Although the mechanism is not yet fully understood, it is thought that exposure to higher levels of natural light acts as a protective effect.

This has also been investigated through interventional studies. A school-based programme in Taiwan, found that encouraging children to spend break time outdoors reduced the onset of myopia (9). In a cluster randomised trial involving almost 1,900 children in Guangzhou, China, adding an additional 40 minutes of outdoor time to each school day reduced the three-year cumulative incidence of myopia from 39.5% to 30.4% (10).

More recent research has also supported these findings. A randomised controlled trial published in 2022 with over 6,000 children found that increasing outdoor time during the school day was associated with a reduction in myopia incidence and less myopic shift over two years (11). Similarly, another systematic review and meta-analysis published in 2024 found that outdoor interventions reduced the incidence of myopia and were associated with more favourable axial length and refractive outcomes (12).

These findings are of particular interest as increasing time spent outdoors is a relatively simple intervention, which does not require any specialist input.

It is important to note that these trials look at prevention of the onset of myopia in non-myopic children. The effects of increased outdoor time on slowing progression in children with known myopia are less certain.

This highlights the importance of encouraging outdoor activity from an early age, prior to the development of myopia. Currently screen time continues to receive public attention in relation to development of myopia, however communicating advice to families about increasing time spent outdoors may be an even more useful message.

Reframing Clinical Advice

Given the evidence, advice regarding children’s eye health should not solely focus on reducing screen time.

Although it continues to remain appropriate to encourage regular breaks during prolonged screen use, clinicians should also consider how much time children are spending outdoors and the nature of their other near-work activities.

Families should be encouraged to include regular daily outdoor activity, particularly earlier in childhood. Advice should also be provided regarding other near-work activities including studying and reading, rather than solely focusing on digital devices. It is important to prioritise regular breaks and appropriate working distances, whether the task is involving a screen, a book or even homework. Parents should also be reassured that there is currently no evidence that normal screen use damages the retina and that blue-light filtering glasses have not shown clear benefits in reduction of eye strain.

This approach has several advantages, from a previously more restrictive message to practical advice that can be more easily adopted into daily life. It remains consistent with the wider public health guidance encouraging physical activity in children, whilst also recognising that screens are commonly used for communication and education purposes so complete avoidance is not realistic.

Ophthalmologists and other healthcare professionals have an important role in communicating these messages to families to ensure informed decisions can be made regarding children’s eye health.

Challenges and Considerations

Although increasing time spent outdoors is supported by evidence, reframing the more prominent narrative may present with several challenges.  

Increasing outdoor activity time may be more difficult for some families, especially those living in urban environments. Poor weather conditions, family commitments and even school schedules may also affect how much time children can spend outside. Hence, the advice provided needs to be realistic and appropriate for individual families, in order not to inadvertently widen health inequalities.  

It is also vital not to dismiss concerns about screen use. There is an association between myopia and screen time, even if its direct causal relationship has not been established, observational studies confirm an association. Excessive screen use may also have negative effects on children’s sleep and physical activity.

Another factor to consider is that most of the evidence supporting increased outdoor time comes from studies in East Asia. The protective effect may not be identical in UK children given differences in environmental exposure and myopia prevalence.

Further research is required to understand the independent role of near work, outdoor activity and screen use in myopia development.

The aim is to ensure a balance of advice, both recognising the concerns of screen use and the current stronger evidence supporting the protective nature of increasing outdoor time.

Conclusion

Public concern about the effects of screens on children’s eyes has increased along with the increasing prevalence of childhood myopia. Although research has shown an association between screen time and myopia, finding a direct causal relationship remains challenging due to the influence of reduced time outdoors and other near-work activities.

There is currently no convincing clinical evidence which supports blue light from screens causes retinal damage, with blue light glasses showing little to no benefit in reducing eye strain.

In comparison, the protective effect of increased time spent outdoors can reduce the risk of developing myopia, as supported by randomised controlled trials.

Ophthalmologists should therefore place greater emphasis on promoting increased time outdoors and sensible near-work activities, rather than solely focusing on screen-time reduction. The most important question to ask a parent may not be how long their child is spending looking at screens, but rather how long they are spending outside.

References

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