School-age children spend much more time outdoors than adults. The lens of children’s eyes has less ability to filter UV rays, which allows the rays to penetrate deep into the eye where there is a risk of damage.
Protecting the eyes at a young age reduces the potential for serious eye problems in adulthood and old age (cataracts, damage to the retina and surface of the eye). UV damage to the eye is cumulative, so we do not see it immediately, but the risk of it manifesting itself in the future increases.