How digital devices are triggering a myopia crisis

In 2020, with no vaccine in sight, the public authorities declared a lockdown to contain the spread of the Covid-19 virus that killed lakhs. Offices and schools were shut down and, thanks to the user-friendly interface Zoom and similar video-conferencing platforms, a new culture of work-from-home was born. Fueled by the uncertainty of the lockdowns and the fear of missing out on academic activities, the young children and toddlers got cooped up in their homes for several hours a day to attend online classes, a new paradigm in pedagogy.

Web-based education had been discussed for decades before the Covid-19 pandemic. The consequences of young children hooked to their digital notebooks and devices escaped the notice of one and all.

Alarm bells rang when ophthalmic epidemiologists in China and later in the rest of the world discovered that by 2020, young children were becoming nearsighted (myopic) at an alarming pace. An increase of 400 per cent in the prevalence of myopia was noted among six-year-olds in China. Before Covid-19, Australian researchers had found that nearsighted children spent an average of one and a half hours more in near activities than the normal-sighted. Keeping books less than 30 cm from one's face and continuously reading for more than 30 minutes are major risk factors for myopia progression in young children.

Nearsightedness (myopia) means the inability to see distant objects, such as what the teacher writes on the blackboard, while reading and writing remain unaffected. An intricate balance in three critical components — the power of the front lens (cornea), the dynamic biconvex crystalline lens and, notably, the eyeball's size — decides whether the image will be focused on the retina or form a blur in front or behind the retina.

For reading, a dynamic increase in the power of the crystalline lens in the young up to +8 diopters allows clear focus. If the eyeball happens to be longer than optimal, a blurred image is formed in front of the retina. This requires wearing minus lenses (myopic glasses) for clear distance vision.

The eyeball measures about 16 mm at birth. In the first two years of life, orchestrated growth in the three elements mentioned earlier occurs, reaching about three-fourths of the adult size of 24 mm. It gets there during the second spurt of growth at puberty (10-16 years). More than 30 years ago, Dr Stone from Philadelphia discovered that levels of a neurotransmitter, dopamine (reward hormone), in the retina control the growth of the eyeball.

My chief, Dr IS Jain, who extensively surveyed both urban and rural populations in the 1960s, blamed excessive near-work, higher literacy rates and income levels for a progressive increase in the prevalence of myopia from the rural (2.77 per cent) to schoolchildren (4.79 per cent), Chandigarh's urban population (6.9 per cent) and the PGI doctors (33 per cent).

Recently, 21 per cent of school-going urban children in north India were detected with myopia, a four-time increase in 50 years.

While the impact of Covid-19 quarantine on progressive myopia was the earliest and most felt in East and South East Asia, no one escaped. According to one study, 46 per cent of children who spent an average of one hour daily on digital devices were myopic compared to 76 per cent of those who spent four hours. Low outdoor activity, dim room illumination and excessive near-work were blamed.

Dr Rohan Hughes and colleagues in Brisbane have found an immediate increase in the axial length of the eyeball in young children, even up to 16 microns, on reading or looking at a nearby object.

In the last 10 years, the use of digital devices has increased fourfold, with even two-year-olds in Singapore reportedly spending up to two hours a day in front of screens. A recent analysis in the prestigious JAMA journal made headlines worldwide. It reported that, based on scientific studies involving more than 3,00,000 schoolchildren, every hour spent on digital screens until at least four hours a day increased the odds of developing myopia by 21 per cent.

While increasing the axial length of the eyeball up to 2 mm (-6D) requires only corrective glasses, any increase beyond this may cause pathological changes that threaten irreversible vision impairment and blindness. While Dr Jain noted high myopia (more than 6D) in only 7 per cent of all myopes 50 years ago, it is currently staggeringly high in Asian countries, reaching more than 20 per cent of young myopic children in South Korea. Nearly 8 per cent of all high myopes face blindness later in life. The numbers could become a major public health concern if Dr Holden and colleagues' predictions of half the world population becoming myopic by 2050 come true.

Twenty years ago, Dr Chua and colleagues from Singapore convincingly demonstrated that using atropine eye drops (a relaxant of muscles for accommodation in the eye) prevents eyeball elongation in young children and decreases myopia progression. Notwithstanding minimal side-effects in some, it being the most cost-effective strategy, atropine drops caught the fancy of eye specialists worldwide, including in India. A pan-India study helmed by Dr Rohit Saxena found that diluted atropine drops (0.01 per cent) decreased myopia progression in Indian children over two years. Higher concentrations of atropine are effective in those who show a rapid progression of myopia.

Exposure to sunlight increases the dopamine levels in the retina and prevents the elongation of the eyeball in several laboratory animals, a fact confirmed in children by Dr Fatih Aslan and Dr Nedime Sahinoglu-Keskek from Turkey, who noted that spending two hours outdoors daily during the Covid-19 pandemic prevented myopia progression. Dr Shweta Chaurasia and colleagues from the PGIMER, Chandigarh, discovered that atropine was more effective if the outdoor activities exceeded two hours or more daily. The two-hour time outdoors does not have to be continuous. Even stepping out for a few minutes at a time works. An eye specialist must closely observe children on atropine treatment.

In a paradoxical move, the National Education Policy 2020, focussing on experiential and holistic learning, dismantled the essential playground requirement mandated in the Right to Education Act of 2008 on the pretext of space constraints in urban India. Let the teachers allow the children outdoors at least one hour twice a day.