Subjective experience is inherently a deceptive lens through which to make medical decisions (e.g. placebo effect).
This is why all clinical guidelines issued by all major medical professional associations rely on expert review of published clinical research, which ostensibly (by using large numbers of participants, a placebo treatment group, double blinding of patient/observer, etc) provides a more objective picture of the relative efficacy of a given intervention. Not only that, but because not all research is created equal, experts try to convey to clinicians reading their guidelines the relative quality and strength of the available evidence (usually on a grading scale from A-E).
So, how do I explain your experience? I don't have a great answer for you, and you shouldn't expect one - particularly in something as challenging as vision, which relies on self-reporting of your subjective impression of your visual acuity (vs something objective and quantifiable like blood pressure).
Maybe these exercises are improving your eyesight (per available evidence, this less likely). Maybe they are not, but you perceive your eyesight to be improved (placebo effect). Maybe you are experiencing an improvement in your vision for reasons unrelated (time of day/ambient light, relative degree of recent eye strain, etc) but you are attributing this improvement to the exercises. Who knows?
At the end of the day, I can't explain your subjective visual improvement and I certainly would not say that your experience is "wrong." Because these exercises cost you (presumably) no money and have effectively 0 risk of causing you harm, I would certainly not tell you to stop. However, I am sure you can imagine that if clinicians made all medical decisions based on a similar degree of subjectivity and intuition, we would hurt a lot of people.
Long story short: research can't explain everything, but it provides a degree of objectivity that can can tell us what is most likely. Most likely, your subjective improvement is due to a placebo effect. That doesn't mean your experience is "wrong," or that you are foolish for trying, or that there isn't a very small chance that it is helping you in a way inconsistent with available evidence.
LMAO... like all the other docs... hmm... never seen that before I don't know whats wrong with you.... story of my life...