The aetiology of myopia is multifactorial, involving interplay between environmental and genetic factors. The recent precipitous rise in myopia prevalence, however, is believed to be the consequence of environmental and lifestyle change. Decreased time outdoors, urbanisation, increased time spent in education and time spent reading continuously or in long periods of close work, have been identified as risk factors for myopia onset or progression. In the midst of a technological age, children are now exposed to another possible environmental risk factor for myopia – digital devices.
Smartphones, tablets and computers are widely used at a very early age in both home and school environments. Smartphones, in particular, have become a ubiquitous part of modern life. Children are the fastest growing population of smartphone users, which is reflected in recent usage statistics internationally. In the USA, for example, 95% of teenagers either own or have access to a smartphone. Smartphones are now the most used device for Internet access by 9 to 16-year-olds in Ireland, with more children owning smartphones than tablets, while 85% of young people in the UK (aged 12-15) use a smartphone daily.
Several studies have identified computer usage as a risk factor for myopia. In fact, one study found myopia was associated with a closer computer screen working distance. The working distance adopted by smartphone users is typically even closer than for computer screens. The smaller size of a smartphone screen necessitates smaller text sizes and closer working distances, potentially increasing peripheral retinal defocus and placing greater demands on the visual system. It is conceivable, therefore, that increased and continuous exposure to a smartphone screen might represent a plausible risk factor for the development or progression of myopia, especially in younger age groups.
So, what does this mean for our eyes? Our evolved lifestyle habits have been driving the myopia epidemic long before the advent of the smartphone, but the current generation of children are the first to grow up in an era of smartphone addiction. Our use of technology has undeniably evolved rapidly over the past ten years, with electronic visual display technology now at the forefront in many schools and workplaces. Today’s children are growing up in a world saturated with technology that demands proximal attention and competes for their leisure time at the expense of healthier outdoor alternatives, with the average youth now spending one-third of each day engaged in some form of electronic media.
The public health implications of a continued increase in short-sightedness include a range of adverse societal, economic, educational and quality of life impacts.
This radical change in the lifestyle habits of children and young people may pose a new and independent risk factor that could drive the myopia epidemic even further than is currently predicted. It has been estimated that myopia will affect 5 billion people worldwide by 2050, with 1 billion expected to have high myopia. Myopia is a risk factor for disease, a source of disability for many visually impaired people worldwide and is now recognised as a disease and classified as an international health priority by the World Health Organisation. The public health implications of a continued increase in myopia include a range of adverse societal, economic, educational and quality of life impacts.
Investigating whether smartphone usage is contributing to myopia development and progression is an important research question in relation to the design and implementation of public health strategies for myopia control and prevention. To understand the risks posed by smartphone usage, we have initiated a number of research studies at the Centre for Eye Research Ireland (CERI), specifically focused on its relationship with myopia. In a ground-breaking study involving 418 primary, secondary and tertiary level students, we have documented the first evidence that smartphone use is higher among myopic students.
Unlike most studies which track lifestyle habits solely using self-reported information (e.g. asking children to estimate the amount of time they spend on various tasks), a novel feature of our study involved the measurement of smartphone data use (including WiFi and mobile data) to provide a more robust measure of smartphone consumption. Using this technique, we observed a very significant association between myopia status and smartphone data usage, with short-sighted students using almost double the amount of mobile phone data daily compared to students who were not short-sighted.
Other important findings from the study, which has been submitted for publication to the British Journal of Ophthalmology, include that students spend almost one third of their day using their smartphone. To put this into context, this is just below the National Sleep Foundation’s recommended sleep duration of over seven hours per night for teenagers and young adults. On top of this, 84 percent of participating students reported using a smartphone in bed every night, with younger children spending more time on their phone in bed compared to older students.
Student and parental understanding of the causes of myopia is limited. Another study we’ve conducted and recently published has demonstrated a lack of parental understanding of the causes of myopia and a lack of parental concern associated with a diagnosis of myopia in their child. This is particularly important given the impact parents have on children’s behaviour with respect to lifestyle choices, demonstrating an acute need for societal sensitisation to the public health importance of myopia. What’s more, new strategies to control short-sightedness from progressing in children will depend heavily on the informed participation of parents.
While these studies are important, we have yet to provide definitive evidence that smartphone use causes myopia to develop or to progress at a faster rate. A suitably designed longitudinal study will be required to explore this concept further and will be one of our research priorities at CERI over the coming years. It seems certain, however, that smartphone use among children is a health concern for vision and other health domains. How parents can control access to technology for their children is another matter entirely.