The Myopia Epidemic: It’s Not Just About Screen Time
For years, smartphones, tablets, and computers have been blamed for the dramatic rise in nearsightedness, or myopia, worldwide. Whereas digital device use is a factor, emerging research suggests the issue is more complex. Current estimates indicate that if current trends continue, nearly half of the global population will be affected by myopia by 2050. Prevalence has risen from approximately 23% in 2000 to around 34% in 2020, with continued growth anticipated. In some East Asian countries, myopia already affects nine out of ten young adults.
Beyond the Screens: The Role of Light and Distance
Experts at the SUNY College of Optometry propose that the primary driver of the myopia epidemic isn’t solely electronic devices, but a combination of prolonged near function (reading, writing, using close-up devices) and insufficient bright light exposure.
When outdoors in sunlight, the pupil naturally constricts to protect the eye while still allowing sufficient light to reach the retina. However, focusing on close objects indoors causes accommodation – the lens changes shape, the pupil narrows to increase depth of field, and the eyes converge for better focus.
In low light conditions, this combination of near work and constricted pupils significantly reduces retinal illumination. “In bright outdoor light, the pupil also narrows, but enough rays still fall on the retina,” explains researcher Urusha Maharjan. “But when we look at a cell phone in the dark, our pupil constricts because of focus, not because of brightness. This combination can then dramatically reduce the amount of rays hitting the fundus of the eye.”
How Reduced Retinal Illumination Impacts Eye Growth
Insufficient stimulation of the retina can disrupt the mechanisms regulating eyeball growth. Myopic individuals have slightly elongated eyeballs, making distant focus difficult. Research indicates that people with existing myopia exhibit even stronger eye convergence and pupil constriction. Myopia can also interfere with the natural blinking reflex.
Repeated and prolonged near focus can lead to a gradual strengthening of pupil constriction. Excessively strong corrective lenses may exacerbate this effect by further narrowing the pupil and reducing retinal illumination. This could explain the benefits observed with outdoor time, atropine eye drops, and multifocal lenses.
The Protective Power of Sunlight
Outdoor environments provide significantly more light, and the pupil primarily reacts to brightness. Modern lifestyles increasingly favor indoor activities over outdoor exposure to sunlight. Studies consistently demonstrate that increased time spent outdoors and exposure to daylight are associated with a lower incidence of myopia, likely due to the effect of light on eye biochemistry. [1]
Global Trends and Projections
The global prevalence of myopia is substantial, affecting approximately one-third of children and adolescents, with variations across demographics. Projections indicate that the global incidence of myopia will exceed 740 million cases by 2050. [1]
Recent studies focusing on China reveal that myopia prevalence has plateaued in urban areas since 2006 and in rural areas since 2013, with the urban-rural gap narrowing. [2] Projections for China estimate a stabilization of myopia prevalence at 27.1% (95% CI: 10.0–44.4%) for ages 7–9, and 81.5% (74.7–88.3%) for ages 16–18 in urban areas by 2050, and 20.1% (8.6–31.7%) and 74.1% (63.2–84.8%) in rural areas. [2]
In South Korea, myopia prevalence increased from 50.6% in 2011 to 59.8% in 2023, with high myopia rising from 14.3% to 17.7%. [3] Projections suggest that by 2050, myopia prevalence may reach 84% and high myopia 28%. [3]
Prevention Strategies
While further research is needed to fully understand these mechanisms, it’s clear that prevention isn’t solely about reducing screen time. Maintaining bright lighting and limiting excessive eye strain during near work could contribute to vision protection. When engaging in prolonged reading or device use, ensure adequate illumination and take regular breaks to look at distant objects.