Axial elongation

Axial elongation is an increase in the axial length of the eyeball. This results in a higher degree of myopia, which is exactly what we're trying to avoid!

Axial elongation in a lens-induced myopia context is primarily caused by hyperopic defocus, typically close-up activity while wearing glasses that are too powerful for the distance in question.

It can also be induced by long periods of accommodation, excessive myopic defocus (don't reduce too much!), or form deprivation from things like diffusers.