4 ms·
So some background information is necessary to get everyone on the same page. The optics of the eye are such that the lens and cornea focus light onto the back
by epmaybe 7y ago
So some background information is necessary to get everyone on the same page. The optics of the eye are such that the lens and cornea focus light onto the back of the eye, the retina. That focusing power can be inadequate or overpowered depending on the axial length of the eye. You can imagine that you would need a diverging lens to help focus light better in a longer (myopic, or near-sighted) eye, and a converging light to help focus light better in a shorter (hyperopic, or far-sighted) eye.
We know from several large scale studies that eye reaches its maximum axial length by around age 13, and while the eye gets ever so slightly shorter (hyperopic, rather than myopic) as you age, it's far outweighed by the effects of presbyopia, whereby the lens of your eye becomes less elastic with age, and thus is unable to focus up close. In effect, it makes you more farsighted, and why people with myopia feel that their vision somewhat improves with age.
Sources (with references to the large scale studies, which unfortunately I cannot currently access): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4347057/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4347057/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3843406/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3843406/