Digital eye strain in kids

Digital eye strain is an often cited cause of asthenopia after (extended) screen use and can encompass a range of eye conditions from dry eyes to binocular vision dysfunctions to even glare sensitivity. In children, the implications of digital eye strain are not trivial: coupled with extensive digital screen use is the concern of myopia onset and progression. So, what exactly should we be aware of when it comes to children and digital devices?

The ongoing COVID-19 pandemic is an unprecedented phenomenon; however, lockdowns have provided a unique opportunity to explore the effect of acute changes to the visual environment on children’s vision – see our article Post-COVID-19 And Myopia: What’s Next For Children’s Vision? Among all age groups and across multiple countries, screen time increased from pre-COVID times even among children younger than school age^.1 The restrictions on outdoor activities and home learning meant digital device usage increased. During these restrictions, reports of digital eye strain consequently rose to 50-60% in the paediatric population.²

Digital eye strain includes a variety of symptoms all arising from the prolonged use of digital devices. These include red, sore, or itchy eyes; watering; foreign body sensation in the eyes; headaches and blurring of the vision.² During home confinement, a study involving children aged 6 to 8 years old in Hong Kong found increased time spent on screens from 2.5 hours per day to 6.9 hours per day.³ A study in India involving children aged 10 to 16 years old showed that screen time increased from 1.9 hours per day to 3.9 hours per day.^4,5 And it’s not just older children: even among children under 3 years of age, screen time increased despite the lack of schooling demands in this age group.⁵ Digital eye strain symptoms can be proportional to the length of time spent on a digital device, so with this almost widespread increase in screen time, an increase in digital eye strain among all age groups is not surprising.

It is notable that the symptoms of digital eye strain² show correlation with symptoms typically reported in dry eye syndrome. Dry eye symptoms from digital device use largely occur due to reduced blink rate. Continuous viewing of a screen is known to reduce blink rate significantly: one study found this can change from 18.4 blinks per minute to 3.6 per minute when using a computer.⁶ Blinking is an essential process to maintain the ocular surface and tear film integrity. The cycle of tear secretion to wet the ocular surface, evaporation and then drainage through the puncta that occurs at every blink allows for normal ocular surface homeostasis and health.⁷

There is a lack of research about dry eye disease in the paediatric population. This may be due to a lack of diagnosis for dry eye disease in children: children are less likely to complain of dry eye symptoms, and tend to report less severity of symptoms than adults with the same clinical dry eye signs.⁸ However, paediatric dry eye disease is not as uncommon as may be suspected: in a 2016 case-control study conducted in Korea of one thousand 6 to 11 year old children, dry eye disease was found in 9% of children aged 9 to 11 years old, and was found in 4% of children aged 6 to 8 years old. It was also found that 71% of those with dry eye disease were smartphone users.⁹ Smartphone use is associated with dry eye disease more so than any other digital device.¹⁰

Dry eye disease tends to be chronic in nature: with a longer duration of the condition, comes the likelihood of worsening symptoms over time.11 Hence, when examining a child reporting symptoms of digital eye strain, dry eye disease is an important differential to investigate and manage appropriately if found.

Digital eye strain can also be the result of the binocular vision system being aggravated by extensive near work and screen time. Interestingly, a series of cases have documented acute acquired concomitant esotropia (AACE) in children due to excessive digital device use during the lockdowns of COVID-19. AACE is sudden onset esotropia and symptoms can include headaches, transient or constant blur, and diplopia.¹⁰ Although the aetiology can be varied, the cases reported during the lockdowns were associated with excessive near work arising from digital device use. Cases in Italy of children as young as 4 years old developing AACE from excessive digital device use were reported.¹¹

In India, a retrospective study involving students aged 10 years or older that suffered from AACE found that the precipitating event was sustained near work: the students would be spending time on their laptop or phone for an average of 8 hours a day. The magnitude of esotropia was an average of 23 prism dioptres at distance and 19 for near.¹² Another study in India reported similar findings.¹³ In most cases, severe restriction of laptop, computer and especially smartphone usage for one month effected a full recovery of the condition.^11-13

Since excessive near work can induce severe binocular vision disturbance, early identification of digital eye strain symptoms which could indicate these disorders is important.

Digital screens can be highly illuminated - some people can report sensitivity to glare as a result of staring at a bright screen for long stretches of time. To combat this, squinting often occurs to manage the amount of light entering the eye. This then puts strain on the orbicularis oculi muscle and can cause feelings of eye pain, headache and tiredness.¹⁴

Glare sensitivity is frequent among computer users;¹⁵ the discomfort associated with digital screens can result in a reduction in reading speed,16 and lead to digital eye strain.¹⁴

Eye strain arises from digital device use for various reasons. Particularly with smartphones, viewing distances of digital screens tend to be shorter than that of books or newspapers;¹⁷ this contributes to the demand on the visual system. As mentioned previously, blink rate is also reduced, which can lead to dry eye.⁷ Some tips to educate children on ergonomic use of digital devices are:

1. The elbow rule: keep an elbow-to-hand distance away from books and screens to avoid them being too close to the eyes.
2. The 20/20 rule: take regular breaks from reading to reduce demand on the visual system. Recent research has expanded this to the 20-20-20 rule (take a break every 20 minutes for 20 seconds and look at least 20 feet away), which has shown benefit for reducing digital eye strain and dry eye symptoms in non-presbyopic adult computer users^.18
3.  The two-hour rule: try to limit leisure screen time (outside of school work) to two hours per day in school-aged children.

Check out our Managing Myopia Guidelines Infographics (free to download in several languages) and our article on Screen time guidelines to support you in communicating these key points.

Of course, with regard to the last tip, this comes with certain caveats. According to recommendations by the World Health Organization, the Australian Government Department of Health, and the American Academy of Paediatrics, the amount of screen time for leisure children can enjoy should be based on age, and interacts with guidelines on physical activity. These are:

• Children under two years of age should have no screen time. Watching a screen at a young age can limit time for active play and learning, reduce opportunities for language development, negatively influence their attention skills and affect the development of the full range of eye movement. The exception to this is video-chatting with family, which can encourage language and social development.
• Children aged 2-4 years should have a maximum of 1 hour of screen time per day, ideally co-watching with a parent. Co-watching, like reading a book together, can make screen time useful for language development and learning. In this age group, excessive screen time has been associated with less active, outdoor and creative play; slower development of language skills; poor social skills and an increased risk of being overweight.
• Children of school age (5-17 years) should be limited to 2 hours of sedentary, recreational screen time per day. Break up long periods of sitting as often as possible, and when using screen-based electronic media, positive social interactions and experiences are encouraged. Reducing screen time before bed and removing screens from the bedroom where possible can be important for healthy sleep habits.

Our updated MyKidsVision.org website includes practical, evidence-based information for parents on myopia, treatment options and management processes, including articles on screen time. Consider directing them to the following articles; you can also download this printable QR code sheet to refer parents to specific articles when they are in your practice.

• The childhood visual environment

• All about screen time and close work

• Screen time specific articles for age groups: babies and toddlers, children, teenagers and young adults.

• Case study: How excessive screen time impacts meibomian glands

• Dry eye in myopia management

• Screen time guidelines for children - resources for eye care practitioners

• Post-COVID and myopia: what's next for children's vision?