In East Asian cities, 80–90% of young adults are now myopic. In the UK and US, rates have roughly doubled in 50 years. The genetics haven’t changed that fast. Something in the environment has — and the evidence increasingly points to one factor above all: time spent outdoors.
How myopia develops
Myopia results from the eye growing too long during childhood. The axial growth of the eye is regulated by a feedback loop: when focused clearly on a distant object, a signal slows growth. When focused on a close object — or when the peripheral retina is exposed to a blurred image — the growth inhibition signal is not sent, and the eye elongates.
Outdoor light plays a specific role. Bright sunlight (even on overcast days, outdoor light is 10–100x brighter than indoor light) stimulates retinal dopamine release, which inhibits axial elongation. Children who spend more time outdoors have significantly lower rates of myopia, independent of how much near work they do. The critical factor is not reading or screens per se — it is the loss of outdoor time that accompanies modern indoor life.
An evolutionary perspective
The eye evolved in an outdoor world. Ancestral children spent most waking hours outside, in bright light, viewing distant landscapes. The eye’s growth regulation was calibrated for this environment. When children spend the majority of their waking hours indoors — in dim, close-range visual environments — the feedback system that should be slowing eye growth simply doesn’t receive the signals it needs.
What this means at OQ
OQ does not treat myopia directly. But the relationship between cranial development, orbital mechanics, and visual function is part of how we approach children with developmental and eye-related presentations. For parents concerned about childhood myopia, the evidence most strongly supports maximising outdoor time — ideally 2 hours daily in natural light.
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