Myopic defocus
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Myopic defocus is the technical term used by research papers to describe the blur caused by having the light focused in front of the retina. This is the typical symptom of uncorrected myopia (short-sightedness). Myopic blur can be induced by reduced lenses for myopes or plus lenses and looking in the distance.
Studies in animal subjects have shown it to induce compensatory axial shortening (hyperopia). It is the underlying mechanism exploited for the reduced lens method's myopia reduction.
Appropriate amounts of myopic defocus when paired with a conducive environment induce axial shortening. Excessive myopic defocus or form deprivation (such as blur from diffusers) tend to induce axial elongation, just like hyperopic defocus, or may result in no changes, which is called Blur adaptation.