Post-COVID-19 and myopia: what's next for children's vision?

The last several months have seen more publications on the impact of COVID on myopia incidence and progression. From a visual environment point of view, a study involving 6 to 8 year old children in Hong Kong found that time spent outdoors decreased from 1.3 hours per day pre-COVID to 0.4 hours per day after; while screen time increased from 2.5 hours pre-COVID to 6.9 hours per day afterwards.¹

Data from India found digital device time increased from 1.9 hours to 3.9 hours per day in 10 to 16-year-old children, with almost 40% using digital devices for more than 5 hours a day compared to less than 2% prior.²

It is not surprising that school-aged children had increased screen time during lockdowns, however even younger children without these schooling requirements have shown increased screen time. Multi-country data on children aged 8 months to 3 years of age has shown increased screen time in all children since the onset of COVID, with total screen time during lockdown associated with higher socio-economic status, parental screen time and parental attitudes to screen time.³

The detrimental impact of this visual environment change is obvious, given the links between increased screen time,⁴ less outdoor time⁵ and myopia onset and progression. What is the evidence on how myopia prevalence has changed since COVID?

The link between myopia and screen time specifically is mixed, which could in part be due to screen time data being gathered from subjective questionnaires rather than objective means.⁴

There is a clear relationship between increased near work and myopia but the impact of screen time as separate to non-screen near work is not yet clear. A recent review on the association between screen time and myopia was the first to conduct separate analysis on 'smart devices' (smartphones and tablet computers) as separate from desktop or laptop computer use, or other near-vision tasks which were not screen-based. It was found that smart device screen time alone was associated with myopia, and the relationship was stronger once combined with computer use. The authors highlighted the need for more objective measures of screen time, rather than questionnaires, to further evaluate this relationship.⁴

The Myopic Epidemiology and Intervention Study (MEIS) undertook vision screening of over a million students aged 7 to 18 years, measuring non-cycloplegic autorefraction and visual acuity. Children were screened in June 2019, December 2019 and June 2020, providing data for six months before and six months after the onset of COVID. Myopia prevalence increased from 52.9% in June 2019 to 53.9% in December, jumping to 59.3% in June 2020. High myopia also showed a much greater jump in the six months post-COVID, from 4.1% in June 2019 to 4.2% in December 2019 and then to 5.0% in June 2020. Younger children (grades 1-6) showed double the increase in myopia prevalence than older children (grades 7-12).⁶

Another large population screening study, underway since 2015 in Feicheng, China, included over 190,000 test results. Non-cycloplegic photoscreener refraction was undertaken on children aged 6 to 13 years, and the data was most recently analyzed in July 2020. The authors reported relatively stable mean spherical equivalent refraction results from 2015-2019, however there was an escalation in myopia in 2020, especially in the 6-8 year old groups. Six-year-olds jumped from 6% myopia in 2015-19 to 22% in 2020. Seven-year-olds jumped from 16% to 26% myopia and eight-year-olds from 28% to 37% myopia. Interestingly, children aged 9 to 13 years showed similar myopia prevalence to previous years - COVID-related home confinement did not appear to impact their rates of myopia onset or progression.⁷

A smaller report from a hospital ophthalmology department in India found 46% of children showed at least 1D annual progression post-COVID compared to only 11% beforehand. Rapid progression was predicted most strongly by sun exposure of less than 1 hour per day (odds ratio 23.01), a history of rapid progression (odds ratio 8.5) and mobile phone use for video games (odds ratio 3.46) but interestingly, age was not a significant factor.⁸

It is too early to tell whether the necessities and habits formed over the past two years have unwound, as the world in 2022 finds our 'new normal' - regardless, the impact of more myopes now will be felt in the years to come. The following are recent publications reporting the effect of home confinement and home-based learning on children's vision and ocular health. How these patterns alter in our (hopefully) post-COVID world is yet to be determined.

• Increased incidence of digital eye strain. A parent survey undertaken in India, when children were attending online classes, found 50% suffered digital eye strain. The most common symptoms were itching and headache, with 13% reporting moderate and 11% reporting severe symptoms. Digital eye strain was predicted by use of mobile phone for games, closer device distance (less than 18 inches), longer duration of device use (>5 hours/day), male gender and children over age 14.²
• Reduced efficacy of myopia control treatments. A study of myopic children treated with 0.05% and 0.025% atropine in Korea analyzed outcomes for the year prior to COVID (early 2019 to March 2020) and the year post-COVID (March 2020 to early 2021). Progression in the post-COVID year showed that children aged 5-10 showed faster progression but children aged 11-15 years did not.⁹
• Binocular vision disorders. A case report series from Italy described four children (aged 4, 8, 16 and 16) with acute acquired concomitant esotropia associated with excessive near work during COVID-19 lockdown. Two were myopes, and two were low hyperopes. All reported at least 8 hours per day of tablet or computer use.¹⁰
• More overall myopia. Earlier onset leads to faster progression of myopia and higher risk of reaching high myopia (at least -5.0D). For children whose myopia onset between 3 to 6 years of age, their mean level of myopia at age 11 is -5.5D.¹⁰ The long-term ocular health risks of increased myopia, and especially high myopia, are well known.

1. Discuss screen time. This is a clinical discussion of ongoing importance, and especially now given the enormous lifestyle changes of the last two years. Provide parents compassionate and actionable advice on screen time: limiting leisure time to less than two hours per day, maintaining a reasonable working distance, and taking regular breaks. Read more in Screen Time Guidelines For Children - Resources For Eye Care Practitioners.
2. Discuss outdoor time. Equally important as the screen time discussion, increasing time spent outdoors appears to be most important for delaying myopia onset in pre-myopes. Read more about how to have this conversation in Keys To Communication In Myopia Management.
3. Monitor myopia progression. If the treatment isn't working as expected, consider the effects of recent times as a factor, but also make sure to check compliance and suitability of the treatment for that child. Read more in Why Isn't The Myopia Control Strategy Working?

• Case Study: When myopia management is not working after COVID-19 home confinement

• Science Review: Lifestyle changes for Chinese school children during COVID-19 home confinement

• Science Review: Increased myopia during the COVID-19 Pandemic