Research notwithstanding, it’s my experience that hyperopia (farsightedness) progresses over time in many cases, just like myopia…in all age people. It’s common in kids who wear glasses for hyperopia, and it’s also well known (talk with any good eye doctor…that’s where my info came from) that most people go toward less myopia or more hyperopia between age 40 and 60 or so, even if they don’t do anything special (as long as they aren’t wearing lenses that are way too strong, and giving hyperopic defocus at distance).
Since the eyeball has to shorten to cause hyperopia to progress, why wouldn’t the same thing be able to happen in someone with a negative refractive state, as long as similar conditions are met? As we know, it does happen…that’s how we improve our myopia. It’s possible to even overshoot 0.0 eventually, and become hyperopic when one was formerly myopic (of course, you wouldn’t want to intentionally go past the minor hyperopia/emmetropic low plus range, because then you’re creating a different issue).
But it does happen. People become more farsighted all the time under the right conditions. This is yet another argument (and a very solid one) you can use against people who don’t believe in this stuff. Refractive states are just that…they aren’t diseases that magically progress over time. The eye/brain apparently does not “care” what your refractive starting point or current state is…only the stimuli it’s exposed to. And it reacts to that in a predictable manner by changing its focal length.