Children are so important to us! If your visual system is underdeveloped as a child for various reasons, it affects you for the rest of your life. You could have become an engineer, but because of the visual draw back you barely passed matric and never reached your full potential.
I often see this in our practice.
Also, the visual demands that are on kids today surpass what most visual systems can handle. Such demands often lead to accommodation spasms in the eye, headaches, concentration deficiency, diminished school performance, and could lead to higher levels of Myopia (shortsightedness), which in turn could result in sight threatening conditions like retinal detachment, glaucoma, cataracts, and myopia macula degeneration.
In the past we only prescribed kids with "best corrected" prescription spectacles. Now we don't just prescribe, we treat them and prevent a lot of long term problems.