For a wild animal or human prehistorical ancestors, that arrangement would be adaptive because it allows for alertness to predators or prey at a distance.

The correction for only emmetropic vision is often the reason that patients are advised to keep wearing glasses to read as they age because of presbyopia.

[8] It has long been assumed that wearing corrective spectacles might possibly perturb the process of emmetropization in young children, with this assumption being supported in particular also by animal studies.

[9] However, it is not yet fully understood for which patient groups, if any, the wearing of corrective spectacles in childhood actually impedes emmetropization.

[9] It is still unclear for which hyperopic, non-strabismic children corrective spectacles may translate to a lower strabismus risk.

[15] "Emmetropia" is derived from Greek ἔμμετρος emmetros "well-proportioned" (from ἐν en "in" and μέτρον metron "measure") and ὤψ ōps "sight" (GEN ὠπός ōpos).

Translated literally, the term indicates the condition of an eye's having in itself (i.e., without recourse to corrective lenses or other instruments) the capability to obtain an accurate measurement of an object's physical appearance.